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1/*
2 * loopy.c:
3 *
4 * An implementation of the Nikoli game 'Loop the loop'.
5 * (c) Mike Pinna, 2005, 2006
6 * Substantially rewritten to allowing for more general types of grid.
7 * (c) Lambros Lambrou 2008
8 *
9 * vim: set shiftwidth=4 :set textwidth=80:
10 */
11
12/*
13 * Possible future solver enhancements:
14 *
15 * - There's an interesting deductive technique which makes use
16 * of topology rather than just graph theory. Each _face_ in
17 * the grid is either inside or outside the loop; you can tell
18 * that two faces are on the same side of the loop if they're
19 * separated by a LINE_NO (or, more generally, by a path
20 * crossing no LINE_UNKNOWNs and an even number of LINE_YESes),
21 * and on the opposite side of the loop if they're separated by
22 * a LINE_YES (or an odd number of LINE_YESes and no
23 * LINE_UNKNOWNs). Oh, and any face separated from the outside
24 * of the grid by a LINE_YES or a LINE_NO is on the inside or
25 * outside respectively. So if you can track this for all
26 * faces, you figure out the state of the line between a pair
27 * once their relative insideness is known.
28 * + The way I envisage this working is simply to keep an edsf
29 * of all _faces_, which indicates whether they're on
30 * opposite sides of the loop from one another. We also
31 * include a special entry in the edsf for the infinite
32 * exterior "face".
33 * + So, the simple way to do this is to just go through the
34 * edges: every time we see an edge in a state other than
35 * LINE_UNKNOWN which separates two faces that aren't in the
36 * same edsf class, we can rectify that by merging the
37 * classes. Then, conversely, an edge in LINE_UNKNOWN state
38 * which separates two faces that _are_ in the same edsf
39 * class can immediately have its state determined.
40 * + But you can go one better, if you're prepared to loop
41 * over all _pairs_ of edges. Suppose we have edges A and B,
42 * which respectively separate faces A1,A2 and B1,B2.
43 * Suppose that A,B are in the same edge-edsf class and that
44 * A1,B1 (wlog) are in the same face-edsf class; then we can
45 * immediately place A2,B2 into the same face-edsf class (as
46 * each other, not as A1 and A2) one way round or the other.
47 * And conversely again, if A1,B1 are in the same face-edsf
48 * class and so are A2,B2, then we can put A,B into the same
49 * face-edsf class.
50 * * Of course, this deduction requires a quadratic-time
51 * loop over all pairs of edges in the grid, so it should
52 * be reserved until there's nothing easier left to be
53 * done.
54 *
55 * - The generalised grid support has made me (SGT) notice a
56 * possible extension to the loop-avoidance code. When you have
57 * a path of connected edges such that no other edges at all
58 * are incident on any vertex in the middle of the path - or,
59 * alternatively, such that any such edges are already known to
60 * be LINE_NO - then you know those edges are either all
61 * LINE_YES or all LINE_NO. Hence you can mentally merge the
62 * entire path into a single long curly edge for the purposes
63 * of loop avoidance, and look directly at whether or not the
64 * extreme endpoints of the path are connected by some other
65 * route. I find this coming up fairly often when I play on the
66 * octagonal grid setting, so it might be worth implementing in
67 * the solver.
68 *
69 * - (Just a speed optimisation.) Consider some todo list queue where every
70 * time we modify something we mark it for consideration by other bits of
71 * the solver, to save iteration over things that have already been done.
72 */
73
74#include <stdio.h>
75#include <stdlib.h>
76#include <stddef.h>
77#include <string.h>
78#include <assert.h>
79#include <ctype.h>
80#include <math.h>
81
82#include "puzzles.h"
83#include "tree234.h"
84#include "grid.h"
85#include "loopgen.h"
86
87/* Debugging options */
88
89/*
90#define DEBUG_CACHES
91#define SHOW_WORKING
92#define DEBUG_DLINES
93*/
94
95/* ----------------------------------------------------------------------
96 * Struct, enum and function declarations
97 */
98
99enum {
100 COL_BACKGROUND,
101 COL_FOREGROUND,
102 COL_LINEUNKNOWN,
103 COL_HIGHLIGHT,
104 COL_MISTAKE,
105 COL_SATISFIED,
106 COL_FAINT,
107 NCOLOURS
108};
109
110struct game_state {
111 grid *game_grid; /* ref-counted (internally) */
112
113 /* Put -1 in a face that doesn't get a clue */
114 signed char *clues;
115
116 /* Array of line states, to store whether each line is
117 * YES, NO or UNKNOWN */
118 char *lines;
119
120 unsigned char *line_errors;
121 int exactly_one_loop;
122
123 int solved;
124 int cheated;
125
126 /* Used in game_text_format(), so that it knows what type of
127 * grid it's trying to render as ASCII text. */
128 int grid_type;
129};
130
131enum solver_status {
132 SOLVER_SOLVED, /* This is the only solution the solver could find */
133 SOLVER_MISTAKE, /* This is definitely not a solution */
134 SOLVER_AMBIGUOUS, /* This _might_ be an ambiguous solution */
135 SOLVER_INCOMPLETE /* This may be a partial solution */
136};
137
138/* ------ Solver state ------ */
139typedef struct solver_state {
140 game_state *state;
141 enum solver_status solver_status;
142 /* NB looplen is the number of dots that are joined together at a point, ie a
143 * looplen of 1 means there are no lines to a particular dot */
144 int *looplen;
145
146 /* Difficulty level of solver. Used by solver functions that want to
147 * vary their behaviour depending on the requested difficulty level. */
148 int diff;
149
150 /* caches */
151 char *dot_yes_count;
152 char *dot_no_count;
153 char *face_yes_count;
154 char *face_no_count;
155 char *dot_solved, *face_solved;
156 int *dotdsf;
157
158 /* Information for Normal level deductions:
159 * For each dline, store a bitmask for whether we know:
160 * (bit 0) at least one is YES
161 * (bit 1) at most one is YES */
162 char *dlines;
163
164 /* Hard level information */
165 int *linedsf;
166} solver_state;
167
168/*
169 * Difficulty levels. I do some macro ickery here to ensure that my
170 * enum and the various forms of my name list always match up.
171 */
172
173#define DIFFLIST(A) \
174 A(EASY,Easy,e) \
175 A(NORMAL,Normal,n) \
176 A(TRICKY,Tricky,t) \
177 A(HARD,Hard,h)
178#define ENUM(upper,title,lower) DIFF_ ## upper,
179#define TITLE(upper,title,lower) #title,
180#define ENCODE(upper,title,lower) #lower
181#define CONFIG(upper,title,lower) ":" #title
182enum { DIFFLIST(ENUM) DIFF_MAX };
183static char const *const diffnames[] = { DIFFLIST(TITLE) };
184static char const diffchars[] = DIFFLIST(ENCODE);
185#define DIFFCONFIG DIFFLIST(CONFIG)
186
187/*
188 * Solver routines, sorted roughly in order of computational cost.
189 * The solver will run the faster deductions first, and slower deductions are
190 * only invoked when the faster deductions are unable to make progress.
191 * Each function is associated with a difficulty level, so that the generated
192 * puzzles are solvable by applying only the functions with the chosen
193 * difficulty level or lower.
194 */
195#define SOLVERLIST(A) \
196 A(trivial_deductions, DIFF_EASY) \
197 A(dline_deductions, DIFF_NORMAL) \
198 A(linedsf_deductions, DIFF_HARD) \
199 A(loop_deductions, DIFF_EASY)
200#define SOLVER_FN_DECL(fn,diff) static int fn(solver_state *);
201#define SOLVER_FN(fn,diff) &fn,
202#define SOLVER_DIFF(fn,diff) diff,
203SOLVERLIST(SOLVER_FN_DECL)
204static int (*(solver_fns[]))(solver_state *) = { SOLVERLIST(SOLVER_FN) };
205static int const solver_diffs[] = { SOLVERLIST(SOLVER_DIFF) };
206static const int NUM_SOLVERS = sizeof(solver_diffs)/sizeof(*solver_diffs);
207
208struct game_params {
209 int w, h;
210 int diff;
211 int type;
212};
213
214/* line_drawstate is the same as line_state, but with the extra ERROR
215 * possibility. The drawing code copies line_state to line_drawstate,
216 * except in the case that the line is an error. */
217enum line_state { LINE_YES, LINE_UNKNOWN, LINE_NO };
218enum line_drawstate { DS_LINE_YES, DS_LINE_UNKNOWN,
219 DS_LINE_NO, DS_LINE_ERROR };
220
221#define OPP(line_state) \
222 (2 - line_state)
223
224
225struct game_drawstate {
226 int started;
227 int tilesize;
228 int flashing;
229 int *textx, *texty;
230 char *lines;
231 char *clue_error;
232 char *clue_satisfied;
233};
234
235static char *validate_desc(const game_params *params, const char *desc);
236static int dot_order(const game_state* state, int i, char line_type);
237static int face_order(const game_state* state, int i, char line_type);
238static solver_state *solve_game_rec(const solver_state *sstate);
239
240#ifdef DEBUG_CACHES
241static void check_caches(const solver_state* sstate);
242#else
243#define check_caches(s)
244#endif
245
246/*
247 * Grid type config options available in Loopy.
248 *
249 * Annoyingly, we have to use an enum here which doesn't match up
250 * exactly to the grid-type enum in grid.h. Values in params->types
251 * are given by names such as LOOPY_GRID_SQUARE, which shouldn't be
252 * confused with GRID_SQUARE which is the value you pass to grid_new()
253 * and friends. So beware!
254 *
255 * (This is partly for historical reasons - Loopy's version of the
256 * enum is encoded in game parameter strings, so we keep it for
257 * backwards compatibility. But also, we need to store additional data
258 * here alongside each enum value, such as names for the presets menu,
259 * which isn't stored in grid.h; so we have to have our own list macro
260 * here anyway, and C doesn't make it easy to enforce that that lines
261 * up exactly with grid.h.)
262 *
263 * Do not add values to this list _except_ at the end, or old game ids
264 * will stop working!
265 */
266#define GRIDLIST(A) \
267 A("Squares",SQUARE,3,3) \
268 A("Triangular",TRIANGULAR,3,3) \
269 A("Honeycomb",HONEYCOMB,3,3) \
270 A("Snub-Square",SNUBSQUARE,3,3) \
271 A("Cairo",CAIRO,3,4) \
272 A("Great-Hexagonal",GREATHEXAGONAL,3,3) \
273 A("Octagonal",OCTAGONAL,3,3) \
274 A("Kites",KITE,3,3) \
275 A("Floret",FLORET,1,2) \
276 A("Dodecagonal",DODECAGONAL,2,2) \
277 A("Great-Dodecagonal",GREATDODECAGONAL,2,2) \
278 A("Penrose (kite/dart)",PENROSE_P2,3,3) \
279 A("Penrose (rhombs)",PENROSE_P3,3,3) \
280 A("Great-Great-Dodecagonal",GREATGREATDODECAGONAL,2,2) \
281 /* end of list */
282
283#define GRID_NAME(title,type,amin,omin) title,
284#define GRID_CONFIG(title,type,amin,omin) ":" title
285#define GRID_LOOPYTYPE(title,type,amin,omin) LOOPY_GRID_ ## type,
286#define GRID_GRIDTYPE(title,type,amin,omin) GRID_ ## type,
287#define GRID_SIZES(title,type,amin,omin) \
288 {amin, omin, \
289 "Width and height for this grid type must both be at least " #amin, \
290 "At least one of width and height for this grid type must be at least " #omin,},
291enum { GRIDLIST(GRID_LOOPYTYPE) };
292static char const *const gridnames[] = { GRIDLIST(GRID_NAME) };
293#define GRID_CONFIGS GRIDLIST(GRID_CONFIG)
294static grid_type grid_types[] = { GRIDLIST(GRID_GRIDTYPE) };
295#define NUM_GRID_TYPES (sizeof(grid_types) / sizeof(grid_types[0]))
296static const struct {
297 int amin, omin;
298 char *aerr, *oerr;
299} grid_size_limits[] = { GRIDLIST(GRID_SIZES) };
300
301/* Generates a (dynamically allocated) new grid, according to the
302 * type and size requested in params. Does nothing if the grid is already
303 * generated. */
304static grid *loopy_generate_grid(const game_params *params,
305 const char *grid_desc)
306{
307 return grid_new(grid_types[params->type], params->w, params->h, grid_desc);
308}
309
310/* ----------------------------------------------------------------------
311 * Preprocessor magic
312 */
313
314/* General constants */
315#define PREFERRED_TILE_SIZE 32
316#define BORDER(tilesize) ((tilesize) / 2)
317#define FLASH_TIME 0.5F
318
319#define BIT_SET(field, bit) ((field) & (1<<(bit)))
320
321#define SET_BIT(field, bit) (BIT_SET(field, bit) ? FALSE : \
322 ((field) |= (1<<(bit)), TRUE))
323
324#define CLEAR_BIT(field, bit) (BIT_SET(field, bit) ? \
325 ((field) &= ~(1<<(bit)), TRUE) : FALSE)
326
327#define CLUE2CHAR(c) \
328 ((c < 0) ? ' ' : c < 10 ? c + '0' : c - 10 + 'A')
329
330/* ----------------------------------------------------------------------
331 * General struct manipulation and other straightforward code
332 */
333
334static game_state *dup_game(const game_state *state)
335{
336 game_state *ret = snew(game_state);
337
338 ret->game_grid = state->game_grid;
339 ret->game_grid->refcount++;
340
341 ret->solved = state->solved;
342 ret->cheated = state->cheated;
343
344 ret->clues = snewn(state->game_grid->num_faces, signed char);
345 memcpy(ret->clues, state->clues, state->game_grid->num_faces);
346
347 ret->lines = snewn(state->game_grid->num_edges, char);
348 memcpy(ret->lines, state->lines, state->game_grid->num_edges);
349
350 ret->line_errors = snewn(state->game_grid->num_edges, unsigned char);
351 memcpy(ret->line_errors, state->line_errors, state->game_grid->num_edges);
352 ret->exactly_one_loop = state->exactly_one_loop;
353
354 ret->grid_type = state->grid_type;
355 return ret;
356}
357
358static void free_game(game_state *state)
359{
360 if (state) {
361 grid_free(state->game_grid);
362 sfree(state->clues);
363 sfree(state->lines);
364 sfree(state->line_errors);
365 sfree(state);
366 }
367}
368
369static solver_state *new_solver_state(const game_state *state, int diff) {
370 int i;
371 int num_dots = state->game_grid->num_dots;
372 int num_faces = state->game_grid->num_faces;
373 int num_edges = state->game_grid->num_edges;
374 solver_state *ret = snew(solver_state);
375
376 ret->state = dup_game(state);
377
378 ret->solver_status = SOLVER_INCOMPLETE;
379 ret->diff = diff;
380
381 ret->dotdsf = snew_dsf(num_dots);
382 ret->looplen = snewn(num_dots, int);
383
384 for (i = 0; i < num_dots; i++) {
385 ret->looplen[i] = 1;
386 }
387
388 ret->dot_solved = snewn(num_dots, char);
389 ret->face_solved = snewn(num_faces, char);
390 memset(ret->dot_solved, FALSE, num_dots);
391 memset(ret->face_solved, FALSE, num_faces);
392
393 ret->dot_yes_count = snewn(num_dots, char);
394 memset(ret->dot_yes_count, 0, num_dots);
395 ret->dot_no_count = snewn(num_dots, char);
396 memset(ret->dot_no_count, 0, num_dots);
397 ret->face_yes_count = snewn(num_faces, char);
398 memset(ret->face_yes_count, 0, num_faces);
399 ret->face_no_count = snewn(num_faces, char);
400 memset(ret->face_no_count, 0, num_faces);
401
402 if (diff < DIFF_NORMAL) {
403 ret->dlines = NULL;
404 } else {
405 ret->dlines = snewn(2*num_edges, char);
406 memset(ret->dlines, 0, 2*num_edges);
407 }
408
409 if (diff < DIFF_HARD) {
410 ret->linedsf = NULL;
411 } else {
412 ret->linedsf = snew_dsf(state->game_grid->num_edges);
413 }
414
415 return ret;
416}
417
418static void free_solver_state(solver_state *sstate) {
419 if (sstate) {
420 free_game(sstate->state);
421 sfree(sstate->dotdsf);
422 sfree(sstate->looplen);
423 sfree(sstate->dot_solved);
424 sfree(sstate->face_solved);
425 sfree(sstate->dot_yes_count);
426 sfree(sstate->dot_no_count);
427 sfree(sstate->face_yes_count);
428 sfree(sstate->face_no_count);
429
430 /* OK, because sfree(NULL) is a no-op */
431 sfree(sstate->dlines);
432 sfree(sstate->linedsf);
433
434 sfree(sstate);
435 }
436}
437
438static solver_state *dup_solver_state(const solver_state *sstate) {
439 game_state *state = sstate->state;
440 int num_dots = state->game_grid->num_dots;
441 int num_faces = state->game_grid->num_faces;
442 int num_edges = state->game_grid->num_edges;
443 solver_state *ret = snew(solver_state);
444
445 ret->state = state = dup_game(sstate->state);
446
447 ret->solver_status = sstate->solver_status;
448 ret->diff = sstate->diff;
449
450 ret->dotdsf = snewn(num_dots, int);
451 ret->looplen = snewn(num_dots, int);
452 memcpy(ret->dotdsf, sstate->dotdsf,
453 num_dots * sizeof(int));
454 memcpy(ret->looplen, sstate->looplen,
455 num_dots * sizeof(int));
456
457 ret->dot_solved = snewn(num_dots, char);
458 ret->face_solved = snewn(num_faces, char);
459 memcpy(ret->dot_solved, sstate->dot_solved, num_dots);
460 memcpy(ret->face_solved, sstate->face_solved, num_faces);
461
462 ret->dot_yes_count = snewn(num_dots, char);
463 memcpy(ret->dot_yes_count, sstate->dot_yes_count, num_dots);
464 ret->dot_no_count = snewn(num_dots, char);
465 memcpy(ret->dot_no_count, sstate->dot_no_count, num_dots);
466
467 ret->face_yes_count = snewn(num_faces, char);
468 memcpy(ret->face_yes_count, sstate->face_yes_count, num_faces);
469 ret->face_no_count = snewn(num_faces, char);
470 memcpy(ret->face_no_count, sstate->face_no_count, num_faces);
471
472 if (sstate->dlines) {
473 ret->dlines = snewn(2*num_edges, char);
474 memcpy(ret->dlines, sstate->dlines,
475 2*num_edges);
476 } else {
477 ret->dlines = NULL;
478 }
479
480 if (sstate->linedsf) {
481 ret->linedsf = snewn(num_edges, int);
482 memcpy(ret->linedsf, sstate->linedsf,
483 num_edges * sizeof(int));
484 } else {
485 ret->linedsf = NULL;
486 }
487
488 return ret;
489}
490
491static game_params *default_params(void)
492{
493 game_params *ret = snew(game_params);
494
495#ifdef SLOW_SYSTEM
496 ret->h = 7;
497 ret->w = 7;
498#else
499 ret->h = 10;
500 ret->w = 10;
501#endif
502 ret->diff = DIFF_EASY;
503 ret->type = 0;
504
505 return ret;
506}
507
508static game_params *dup_params(const game_params *params)
509{
510 game_params *ret = snew(game_params);
511
512 *ret = *params; /* structure copy */
513 return ret;
514}
515
516static const game_params loopy_presets_top[] = {
517#ifdef SMALL_SCREEN
518 { 7, 7, DIFF_EASY, LOOPY_GRID_SQUARE },
519 { 7, 7, DIFF_NORMAL, LOOPY_GRID_SQUARE },
520 { 7, 7, DIFF_HARD, LOOPY_GRID_SQUARE },
521 { 7, 7, DIFF_HARD, LOOPY_GRID_TRIANGULAR },
522 { 5, 5, DIFF_HARD, LOOPY_GRID_SNUBSQUARE },
523 { 7, 7, DIFF_HARD, LOOPY_GRID_CAIRO },
524 { 5, 5, DIFF_HARD, LOOPY_GRID_KITE },
525 { 6, 6, DIFF_HARD, LOOPY_GRID_PENROSE_P2 },
526 { 6, 6, DIFF_HARD, LOOPY_GRID_PENROSE_P3 },
527#else
528 { 7, 7, DIFF_EASY, LOOPY_GRID_SQUARE },
529 { 10, 10, DIFF_EASY, LOOPY_GRID_SQUARE },
530 { 7, 7, DIFF_NORMAL, LOOPY_GRID_SQUARE },
531 { 10, 10, DIFF_NORMAL, LOOPY_GRID_SQUARE },
532 { 7, 7, DIFF_HARD, LOOPY_GRID_SQUARE },
533 { 10, 10, DIFF_HARD, LOOPY_GRID_SQUARE },
534 { 12, 10, DIFF_HARD, LOOPY_GRID_TRIANGULAR },
535 { 7, 7, DIFF_HARD, LOOPY_GRID_SNUBSQUARE },
536 { 9, 9, DIFF_HARD, LOOPY_GRID_CAIRO },
537 { 5, 5, DIFF_HARD, LOOPY_GRID_KITE },
538 { 10, 10, DIFF_HARD, LOOPY_GRID_PENROSE_P2 },
539 { 10, 10, DIFF_HARD, LOOPY_GRID_PENROSE_P3 },
540#endif
541};
542
543static const game_params loopy_presets_more[] = {
544#ifdef SMALL_SCREEN
545 { 7, 7, DIFF_HARD, LOOPY_GRID_HONEYCOMB },
546 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATHEXAGONAL },
547 { 5, 5, DIFF_HARD, LOOPY_GRID_OCTAGONAL },
548 { 3, 3, DIFF_HARD, LOOPY_GRID_FLORET },
549 { 3, 3, DIFF_HARD, LOOPY_GRID_DODECAGONAL },
550 { 3, 3, DIFF_HARD, LOOPY_GRID_GREATDODECAGONAL },
551 { 3, 2, DIFF_HARD, LOOPY_GRID_GREATGREATDODECAGONAL },
552#else
553 { 10, 10, DIFF_HARD, LOOPY_GRID_HONEYCOMB },
554 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATHEXAGONAL },
555 { 7, 7, DIFF_HARD, LOOPY_GRID_OCTAGONAL },
556 { 5, 5, DIFF_HARD, LOOPY_GRID_FLORET },
557 { 5, 4, DIFF_HARD, LOOPY_GRID_DODECAGONAL },
558 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATDODECAGONAL },
559 { 5, 3, DIFF_HARD, LOOPY_GRID_GREATGREATDODECAGONAL },
560#endif
561};
562
563static void preset_menu_add_preset_with_title(struct preset_menu *menu,
564 const game_params *params)
565{
566 char buf[80];
567 game_params *dup_params;
568
569 sprintf(buf, "%dx%d %s - %s", params->h, params->w,
570 gridnames[params->type], diffnames[params->diff]);
571
572 dup_params = snew(game_params);
573 *dup_params = *params;
574
575 preset_menu_add_preset(menu, dupstr(buf), dup_params);
576}
577
578static struct preset_menu *game_preset_menu(void)
579{
580 struct preset_menu *top, *more;
581 int i;
582
583 top = preset_menu_new();
584 for (i = 0; i < lenof(loopy_presets_top); i++)
585 preset_menu_add_preset_with_title(top, &loopy_presets_top[i]);
586
587 more = preset_menu_add_submenu(top, dupstr("More..."));
588 for (i = 0; i < lenof(loopy_presets_more); i++)
589 preset_menu_add_preset_with_title(more, &loopy_presets_more[i]);
590
591 return top;
592}
593
594static void free_params(game_params *params)
595{
596 sfree(params);
597}
598
599static void decode_params(game_params *params, char const *string)
600{
601 params->h = params->w = atoi(string);
602 params->diff = DIFF_EASY;
603 while (*string && isdigit((unsigned char)*string)) string++;
604 if (*string == 'x') {
605 string++;
606 params->h = atoi(string);
607 while (*string && isdigit((unsigned char)*string)) string++;
608 }
609 if (*string == 't') {
610 string++;
611 params->type = atoi(string);
612 while (*string && isdigit((unsigned char)*string)) string++;
613 }
614 if (*string == 'd') {
615 int i;
616 string++;
617 for (i = 0; i < DIFF_MAX; i++)
618 if (*string == diffchars[i])
619 params->diff = i;
620 if (*string) string++;
621 }
622}
623
624static char *encode_params(const game_params *params, int full)
625{
626 char str[80];
627 sprintf(str, "%dx%dt%d", params->w, params->h, params->type);
628 if (full)
629 sprintf(str + strlen(str), "d%c", diffchars[params->diff]);
630 return dupstr(str);
631}
632
633static config_item *game_configure(const game_params *params)
634{
635 config_item *ret;
636 char buf[80];
637
638 ret = snewn(5, config_item);
639
640 ret[0].name = "Width";
641 ret[0].type = C_STRING;
642 sprintf(buf, "%d", params->w);
643 ret[0].sval = dupstr(buf);
644 ret[0].ival = 0;
645
646 ret[1].name = "Height";
647 ret[1].type = C_STRING;
648 sprintf(buf, "%d", params->h);
649 ret[1].sval = dupstr(buf);
650 ret[1].ival = 0;
651
652 ret[2].name = "Grid type";
653 ret[2].type = C_CHOICES;
654 ret[2].sval = GRID_CONFIGS;
655 ret[2].ival = params->type;
656
657 ret[3].name = "Difficulty";
658 ret[3].type = C_CHOICES;
659 ret[3].sval = DIFFCONFIG;
660 ret[3].ival = params->diff;
661
662 ret[4].name = NULL;
663 ret[4].type = C_END;
664 ret[4].sval = NULL;
665 ret[4].ival = 0;
666
667 return ret;
668}
669
670static game_params *custom_params(const config_item *cfg)
671{
672 game_params *ret = snew(game_params);
673
674 ret->w = atoi(cfg[0].sval);
675 ret->h = atoi(cfg[1].sval);
676 ret->type = cfg[2].ival;
677 ret->diff = cfg[3].ival;
678
679 return ret;
680}
681
682static char *validate_params(const game_params *params, int full)
683{
684 if (params->type < 0 || params->type >= NUM_GRID_TYPES)
685 return "Illegal grid type";
686 if (params->w < grid_size_limits[params->type].amin ||
687 params->h < grid_size_limits[params->type].amin)
688 return grid_size_limits[params->type].aerr;
689 if (params->w < grid_size_limits[params->type].omin &&
690 params->h < grid_size_limits[params->type].omin)
691 return grid_size_limits[params->type].oerr;
692
693 /*
694 * This shouldn't be able to happen at all, since decode_params
695 * and custom_params will never generate anything that isn't
696 * within range.
697 */
698 assert(params->diff < DIFF_MAX);
699
700 return NULL;
701}
702
703/* Returns a newly allocated string describing the current puzzle */
704static char *state_to_text(const game_state *state)
705{
706 grid *g = state->game_grid;
707 char *retval;
708 int num_faces = g->num_faces;
709 char *description = snewn(num_faces + 1, char);
710 char *dp = description;
711 int empty_count = 0;
712 int i;
713
714 for (i = 0; i < num_faces; i++) {
715 if (state->clues[i] < 0) {
716 if (empty_count > 25) {
717 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
718 empty_count = 0;
719 }
720 empty_count++;
721 } else {
722 if (empty_count) {
723 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
724 empty_count = 0;
725 }
726 dp += sprintf(dp, "%c", (int)CLUE2CHAR(state->clues[i]));
727 }
728 }
729
730 if (empty_count)
731 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
732
733 retval = dupstr(description);
734 sfree(description);
735
736 return retval;
737}
738
739#define GRID_DESC_SEP '_'
740
741/* Splits up a (optional) grid_desc from the game desc. Returns the
742 * grid_desc (which needs freeing) and updates the desc pointer to
743 * start of real desc, or returns NULL if no desc. */
744static char *extract_grid_desc(const char **desc)
745{
746 char *sep = strchr(*desc, GRID_DESC_SEP), *gd;
747 int gd_len;
748
749 if (!sep) return NULL;
750
751 gd_len = sep - (*desc);
752 gd = snewn(gd_len+1, char);
753 memcpy(gd, *desc, gd_len);
754 gd[gd_len] = '\0';
755
756 *desc = sep+1;
757
758 return gd;
759}
760
761/* We require that the params pass the test in validate_params and that the
762 * description fills the entire game area */
763static char *validate_desc(const game_params *params, const char *desc)
764{
765 int count = 0;
766 grid *g;
767 char *grid_desc, *ret;
768
769 /* It's pretty inefficient to do this just for validation. All we need to
770 * know is the precise number of faces. */
771 grid_desc = extract_grid_desc(&desc);
772 ret = grid_validate_desc(grid_types[params->type], params->w, params->h, grid_desc);
773 if (ret) return ret;
774
775 g = loopy_generate_grid(params, grid_desc);
776 if (grid_desc) sfree(grid_desc);
777
778 for (; *desc; ++desc) {
779 if ((*desc >= '0' && *desc <= '9') || (*desc >= 'A' && *desc <= 'Z')) {
780 count++;
781 continue;
782 }
783 if (*desc >= 'a') {
784 count += *desc - 'a' + 1;
785 continue;
786 }
787 return "Unknown character in description";
788 }
789
790 if (count < g->num_faces)
791 return "Description too short for board size";
792 if (count > g->num_faces)
793 return "Description too long for board size";
794
795 grid_free(g);
796
797 return NULL;
798}
799
800/* Sums the lengths of the numbers in range [0,n) */
801/* See equivalent function in solo.c for justification of this. */
802static int len_0_to_n(int n)
803{
804 int len = 1; /* Counting 0 as a bit of a special case */
805 int i;
806
807 for (i = 1; i < n; i *= 10) {
808 len += max(n - i, 0);
809 }
810
811 return len;
812}
813
814static char *encode_solve_move(const game_state *state)
815{
816 int len;
817 char *ret, *p;
818 int i;
819 int num_edges = state->game_grid->num_edges;
820
821 /* This is going to return a string representing the moves needed to set
822 * every line in a grid to be the same as the ones in 'state'. The exact
823 * length of this string is predictable. */
824
825 len = 1; /* Count the 'S' prefix */
826 /* Numbers in all lines */
827 len += len_0_to_n(num_edges);
828 /* For each line we also have a letter */
829 len += num_edges;
830
831 ret = snewn(len + 1, char);
832 p = ret;
833
834 p += sprintf(p, "S");
835
836 for (i = 0; i < num_edges; i++) {
837 switch (state->lines[i]) {
838 case LINE_YES:
839 p += sprintf(p, "%dy", i);
840 break;
841 case LINE_NO:
842 p += sprintf(p, "%dn", i);
843 break;
844 }
845 }
846
847 /* No point in doing sums like that if they're going to be wrong */
848 assert(strlen(ret) <= (size_t)len);
849 return ret;
850}
851
852static game_ui *new_ui(const game_state *state)
853{
854 return NULL;
855}
856
857static void free_ui(game_ui *ui)
858{
859}
860
861static char *encode_ui(const game_ui *ui)
862{
863 return NULL;
864}
865
866static void decode_ui(game_ui *ui, const char *encoding)
867{
868}
869
870static void game_changed_state(game_ui *ui, const game_state *oldstate,
871 const game_state *newstate)
872{
873}
874
875static void game_compute_size(const game_params *params, int tilesize,
876 int *x, int *y)
877{
878 int grid_width, grid_height, rendered_width, rendered_height;
879 int g_tilesize;
880
881 grid_compute_size(grid_types[params->type], params->w, params->h,
882 &g_tilesize, &grid_width, &grid_height);
883
884 /* multiply first to minimise rounding error on integer division */
885 rendered_width = grid_width * tilesize / g_tilesize;
886 rendered_height = grid_height * tilesize / g_tilesize;
887 *x = rendered_width + 2 * BORDER(tilesize) + 1;
888 *y = rendered_height + 2 * BORDER(tilesize) + 1;
889}
890
891static void game_set_size(drawing *dr, game_drawstate *ds,
892 const game_params *params, int tilesize)
893{
894 ds->tilesize = tilesize;
895}
896
897static float *game_colours(frontend *fe, int *ncolours)
898{
899 float *ret = snewn(3 * NCOLOURS, float);
900
901 frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
902
903 ret[COL_FOREGROUND * 3 + 0] = 0.0F;
904 ret[COL_FOREGROUND * 3 + 1] = 0.0F;
905 ret[COL_FOREGROUND * 3 + 2] = 0.0F;
906
907 /*
908 * We want COL_LINEUNKNOWN to be a yellow which is a bit darker
909 * than the background. (I previously set it to 0.8,0.8,0, but
910 * found that this went badly with the 0.8,0.8,0.8 favoured as a
911 * background by the Java frontend.)
912 */
913 ret[COL_LINEUNKNOWN * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 0.9F;
914 ret[COL_LINEUNKNOWN * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 0.9F;
915 ret[COL_LINEUNKNOWN * 3 + 2] = 0.0F;
916
917 ret[COL_HIGHLIGHT * 3 + 0] = 1.0F;
918 ret[COL_HIGHLIGHT * 3 + 1] = 1.0F;
919 ret[COL_HIGHLIGHT * 3 + 2] = 1.0F;
920
921 ret[COL_MISTAKE * 3 + 0] = 1.0F;
922 ret[COL_MISTAKE * 3 + 1] = 0.0F;
923 ret[COL_MISTAKE * 3 + 2] = 0.0F;
924
925 ret[COL_SATISFIED * 3 + 0] = 0.0F;
926 ret[COL_SATISFIED * 3 + 1] = 0.0F;
927 ret[COL_SATISFIED * 3 + 2] = 0.0F;
928
929 /* We want the faint lines to be a bit darker than the background.
930 * Except if the background is pretty dark already; then it ought to be a
931 * bit lighter. Oy vey.
932 */
933 ret[COL_FAINT * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 0.9F;
934 ret[COL_FAINT * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 0.9F;
935 ret[COL_FAINT * 3 + 2] = ret[COL_BACKGROUND * 3 + 2] * 0.9F;
936
937 *ncolours = NCOLOURS;
938 return ret;
939}
940
941static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
942{
943 struct game_drawstate *ds = snew(struct game_drawstate);
944 int num_faces = state->game_grid->num_faces;
945 int num_edges = state->game_grid->num_edges;
946 int i;
947
948 ds->tilesize = 0;
949 ds->started = 0;
950 ds->lines = snewn(num_edges, char);
951 ds->clue_error = snewn(num_faces, char);
952 ds->clue_satisfied = snewn(num_faces, char);
953 ds->textx = snewn(num_faces, int);
954 ds->texty = snewn(num_faces, int);
955 ds->flashing = 0;
956
957 memset(ds->lines, LINE_UNKNOWN, num_edges);
958 memset(ds->clue_error, 0, num_faces);
959 memset(ds->clue_satisfied, 0, num_faces);
960 for (i = 0; i < num_faces; i++)
961 ds->textx[i] = ds->texty[i] = -1;
962
963 return ds;
964}
965
966static void game_free_drawstate(drawing *dr, game_drawstate *ds)
967{
968 sfree(ds->textx);
969 sfree(ds->texty);
970 sfree(ds->clue_error);
971 sfree(ds->clue_satisfied);
972 sfree(ds->lines);
973 sfree(ds);
974}
975
976static int game_timing_state(const game_state *state, game_ui *ui)
977{
978 return TRUE;
979}
980
981static float game_anim_length(const game_state *oldstate,
982 const game_state *newstate, int dir, game_ui *ui)
983{
984 return 0.0F;
985}
986
987static int game_can_format_as_text_now(const game_params *params)
988{
989 if (params->type != 0)
990 return FALSE;
991 return TRUE;
992}
993
994static char *game_text_format(const game_state *state)
995{
996 int w, h, W, H;
997 int x, y, i;
998 int cell_size;
999 char *ret;
1000 grid *g = state->game_grid;
1001 grid_face *f;
1002
1003 assert(state->grid_type == 0);
1004
1005 /* Work out the basic size unit */
1006 f = g->faces; /* first face */
1007 assert(f->order == 4);
1008 /* The dots are ordered clockwise, so the two opposite
1009 * corners are guaranteed to span the square */
1010 cell_size = abs(f->dots[0]->x - f->dots[2]->x);
1011
1012 w = (g->highest_x - g->lowest_x) / cell_size;
1013 h = (g->highest_y - g->lowest_y) / cell_size;
1014
1015 /* Create a blank "canvas" to "draw" on */
1016 W = 2 * w + 2;
1017 H = 2 * h + 1;
1018 ret = snewn(W * H + 1, char);
1019 for (y = 0; y < H; y++) {
1020 for (x = 0; x < W-1; x++) {
1021 ret[y*W + x] = ' ';
1022 }
1023 ret[y*W + W-1] = '\n';
1024 }
1025 ret[H*W] = '\0';
1026
1027 /* Fill in edge info */
1028 for (i = 0; i < g->num_edges; i++) {
1029 grid_edge *e = g->edges + i;
1030 /* Cell coordinates, from (0,0) to (w-1,h-1) */
1031 int x1 = (e->dot1->x - g->lowest_x) / cell_size;
1032 int x2 = (e->dot2->x - g->lowest_x) / cell_size;
1033 int y1 = (e->dot1->y - g->lowest_y) / cell_size;
1034 int y2 = (e->dot2->y - g->lowest_y) / cell_size;
1035 /* Midpoint, in canvas coordinates (canvas coordinates are just twice
1036 * cell coordinates) */
1037 x = x1 + x2;
1038 y = y1 + y2;
1039 switch (state->lines[i]) {
1040 case LINE_YES:
1041 ret[y*W + x] = (y1 == y2) ? '-' : '|';
1042 break;
1043 case LINE_NO:
1044 ret[y*W + x] = 'x';
1045 break;
1046 case LINE_UNKNOWN:
1047 break; /* already a space */
1048 default:
1049 assert(!"Illegal line state");
1050 }
1051 }
1052
1053 /* Fill in clues */
1054 for (i = 0; i < g->num_faces; i++) {
1055 int x1, x2, y1, y2;
1056
1057 f = g->faces + i;
1058 assert(f->order == 4);
1059 /* Cell coordinates, from (0,0) to (w-1,h-1) */
1060 x1 = (f->dots[0]->x - g->lowest_x) / cell_size;
1061 x2 = (f->dots[2]->x - g->lowest_x) / cell_size;
1062 y1 = (f->dots[0]->y - g->lowest_y) / cell_size;
1063 y2 = (f->dots[2]->y - g->lowest_y) / cell_size;
1064 /* Midpoint, in canvas coordinates */
1065 x = x1 + x2;
1066 y = y1 + y2;
1067 ret[y*W + x] = CLUE2CHAR(state->clues[i]);
1068 }
1069 return ret;
1070}
1071
1072/* ----------------------------------------------------------------------
1073 * Debug code
1074 */
1075
1076#ifdef DEBUG_CACHES
1077static void check_caches(const solver_state* sstate)
1078{
1079 int i;
1080 const game_state *state = sstate->state;
1081 const grid *g = state->game_grid;
1082
1083 for (i = 0; i < g->num_dots; i++) {
1084 assert(dot_order(state, i, LINE_YES) == sstate->dot_yes_count[i]);
1085 assert(dot_order(state, i, LINE_NO) == sstate->dot_no_count[i]);
1086 }
1087
1088 for (i = 0; i < g->num_faces; i++) {
1089 assert(face_order(state, i, LINE_YES) == sstate->face_yes_count[i]);
1090 assert(face_order(state, i, LINE_NO) == sstate->face_no_count[i]);
1091 }
1092}
1093
1094#if 0
1095#define check_caches(s) \
1096 do { \
1097 fprintf(stderr, "check_caches at line %d\n", __LINE__); \
1098 check_caches(s); \
1099 } while (0)
1100#endif
1101#endif /* DEBUG_CACHES */
1102
1103/* ----------------------------------------------------------------------
1104 * Solver utility functions
1105 */
1106
1107/* Sets the line (with index i) to the new state 'line_new', and updates
1108 * the cached counts of any affected faces and dots.
1109 * Returns TRUE if this actually changed the line's state. */
1110static int solver_set_line(solver_state *sstate, int i,
1111 enum line_state line_new
1112#ifdef SHOW_WORKING
1113 , const char *reason
1114#endif
1115 )
1116{
1117 game_state *state = sstate->state;
1118 grid *g;
1119 grid_edge *e;
1120
1121 assert(line_new != LINE_UNKNOWN);
1122
1123 check_caches(sstate);
1124
1125 if (state->lines[i] == line_new) {
1126 return FALSE; /* nothing changed */
1127 }
1128 state->lines[i] = line_new;
1129
1130#ifdef SHOW_WORKING
1131 fprintf(stderr, "solver: set line [%d] to %s (%s)\n",
1132 i, line_new == LINE_YES ? "YES" : "NO",
1133 reason);
1134#endif
1135
1136 g = state->game_grid;
1137 e = g->edges + i;
1138
1139 /* Update the cache for both dots and both faces affected by this. */
1140 if (line_new == LINE_YES) {
1141 sstate->dot_yes_count[e->dot1 - g->dots]++;
1142 sstate->dot_yes_count[e->dot2 - g->dots]++;
1143 if (e->face1) {
1144 sstate->face_yes_count[e->face1 - g->faces]++;
1145 }
1146 if (e->face2) {
1147 sstate->face_yes_count[e->face2 - g->faces]++;
1148 }
1149 } else {
1150 sstate->dot_no_count[e->dot1 - g->dots]++;
1151 sstate->dot_no_count[e->dot2 - g->dots]++;
1152 if (e->face1) {
1153 sstate->face_no_count[e->face1 - g->faces]++;
1154 }
1155 if (e->face2) {
1156 sstate->face_no_count[e->face2 - g->faces]++;
1157 }
1158 }
1159
1160 check_caches(sstate);
1161 return TRUE;
1162}
1163
1164#ifdef SHOW_WORKING
1165#define solver_set_line(a, b, c) \
1166 solver_set_line(a, b, c, __FUNCTION__)
1167#endif
1168
1169/*
1170 * Merge two dots due to the existence of an edge between them.
1171 * Updates the dsf tracking equivalence classes, and keeps track of
1172 * the length of path each dot is currently a part of.
1173 * Returns TRUE if the dots were already linked, ie if they are part of a
1174 * closed loop, and false otherwise.
1175 */
1176static int merge_dots(solver_state *sstate, int edge_index)
1177{
1178 int i, j, len;
1179 grid *g = sstate->state->game_grid;
1180 grid_edge *e = g->edges + edge_index;
1181
1182 i = e->dot1 - g->dots;
1183 j = e->dot2 - g->dots;
1184
1185 i = dsf_canonify(sstate->dotdsf, i);
1186 j = dsf_canonify(sstate->dotdsf, j);
1187
1188 if (i == j) {
1189 return TRUE;
1190 } else {
1191 len = sstate->looplen[i] + sstate->looplen[j];
1192 dsf_merge(sstate->dotdsf, i, j);
1193 i = dsf_canonify(sstate->dotdsf, i);
1194 sstate->looplen[i] = len;
1195 return FALSE;
1196 }
1197}
1198
1199/* Merge two lines because the solver has deduced that they must be either
1200 * identical or opposite. Returns TRUE if this is new information, otherwise
1201 * FALSE. */
1202static int merge_lines(solver_state *sstate, int i, int j, int inverse
1203#ifdef SHOW_WORKING
1204 , const char *reason
1205#endif
1206 )
1207{
1208 int inv_tmp;
1209
1210 assert(i < sstate->state->game_grid->num_edges);
1211 assert(j < sstate->state->game_grid->num_edges);
1212
1213 i = edsf_canonify(sstate->linedsf, i, &inv_tmp);
1214 inverse ^= inv_tmp;
1215 j = edsf_canonify(sstate->linedsf, j, &inv_tmp);
1216 inverse ^= inv_tmp;
1217
1218 edsf_merge(sstate->linedsf, i, j, inverse);
1219
1220#ifdef SHOW_WORKING
1221 if (i != j) {
1222 fprintf(stderr, "%s [%d] [%d] %s(%s)\n",
1223 __FUNCTION__, i, j,
1224 inverse ? "inverse " : "", reason);
1225 }
1226#endif
1227 return (i != j);
1228}
1229
1230#ifdef SHOW_WORKING
1231#define merge_lines(a, b, c, d) \
1232 merge_lines(a, b, c, d, __FUNCTION__)
1233#endif
1234
1235/* Count the number of lines of a particular type currently going into the
1236 * given dot. */
1237static int dot_order(const game_state* state, int dot, char line_type)
1238{
1239 int n = 0;
1240 grid *g = state->game_grid;
1241 grid_dot *d = g->dots + dot;
1242 int i;
1243
1244 for (i = 0; i < d->order; i++) {
1245 grid_edge *e = d->edges[i];
1246 if (state->lines[e - g->edges] == line_type)
1247 ++n;
1248 }
1249 return n;
1250}
1251
1252/* Count the number of lines of a particular type currently surrounding the
1253 * given face */
1254static int face_order(const game_state* state, int face, char line_type)
1255{
1256 int n = 0;
1257 grid *g = state->game_grid;
1258 grid_face *f = g->faces + face;
1259 int i;
1260
1261 for (i = 0; i < f->order; i++) {
1262 grid_edge *e = f->edges[i];
1263 if (state->lines[e - g->edges] == line_type)
1264 ++n;
1265 }
1266 return n;
1267}
1268
1269/* Set all lines bordering a dot of type old_type to type new_type
1270 * Return value tells caller whether this function actually did anything */
1271static int dot_setall(solver_state *sstate, int dot,
1272 char old_type, char new_type)
1273{
1274 int retval = FALSE, r;
1275 game_state *state = sstate->state;
1276 grid *g;
1277 grid_dot *d;
1278 int i;
1279
1280 if (old_type == new_type)
1281 return FALSE;
1282
1283 g = state->game_grid;
1284 d = g->dots + dot;
1285
1286 for (i = 0; i < d->order; i++) {
1287 int line_index = d->edges[i] - g->edges;
1288 if (state->lines[line_index] == old_type) {
1289 r = solver_set_line(sstate, line_index, new_type);
1290 assert(r == TRUE);
1291 retval = TRUE;
1292 }
1293 }
1294 return retval;
1295}
1296
1297/* Set all lines bordering a face of type old_type to type new_type */
1298static int face_setall(solver_state *sstate, int face,
1299 char old_type, char new_type)
1300{
1301 int retval = FALSE, r;
1302 game_state *state = sstate->state;
1303 grid *g;
1304 grid_face *f;
1305 int i;
1306
1307 if (old_type == new_type)
1308 return FALSE;
1309
1310 g = state->game_grid;
1311 f = g->faces + face;
1312
1313 for (i = 0; i < f->order; i++) {
1314 int line_index = f->edges[i] - g->edges;
1315 if (state->lines[line_index] == old_type) {
1316 r = solver_set_line(sstate, line_index, new_type);
1317 assert(r == TRUE);
1318 retval = TRUE;
1319 }
1320 }
1321 return retval;
1322}
1323
1324/* ----------------------------------------------------------------------
1325 * Loop generation and clue removal
1326 */
1327
1328static void add_full_clues(game_state *state, random_state *rs)
1329{
1330 signed char *clues = state->clues;
1331 grid *g = state->game_grid;
1332 char *board = snewn(g->num_faces, char);
1333 int i;
1334
1335 generate_loop(g, board, rs, NULL, NULL);
1336
1337 /* Fill out all the clues by initialising to 0, then iterating over
1338 * all edges and incrementing each clue as we find edges that border
1339 * between BLACK/WHITE faces. While we're at it, we verify that the
1340 * algorithm does work, and there aren't any GREY faces still there. */
1341 memset(clues, 0, g->num_faces);
1342 for (i = 0; i < g->num_edges; i++) {
1343 grid_edge *e = g->edges + i;
1344 grid_face *f1 = e->face1;
1345 grid_face *f2 = e->face2;
1346 enum face_colour c1 = FACE_COLOUR(f1);
1347 enum face_colour c2 = FACE_COLOUR(f2);
1348 assert(c1 != FACE_GREY);
1349 assert(c2 != FACE_GREY);
1350 if (c1 != c2) {
1351 if (f1) clues[f1 - g->faces]++;
1352 if (f2) clues[f2 - g->faces]++;
1353 }
1354 }
1355 sfree(board);
1356}
1357
1358
1359static int game_has_unique_soln(const game_state *state, int diff)
1360{
1361 int ret;
1362 solver_state *sstate_new;
1363 solver_state *sstate = new_solver_state((game_state *)state, diff);
1364
1365 sstate_new = solve_game_rec(sstate);
1366
1367 assert(sstate_new->solver_status != SOLVER_MISTAKE);
1368 ret = (sstate_new->solver_status == SOLVER_SOLVED);
1369
1370 free_solver_state(sstate_new);
1371 free_solver_state(sstate);
1372
1373 return ret;
1374}
1375
1376
1377/* Remove clues one at a time at random. */
1378static game_state *remove_clues(game_state *state, random_state *rs,
1379 int diff)
1380{
1381 int *face_list;
1382 int num_faces = state->game_grid->num_faces;
1383 game_state *ret = dup_game(state), *saved_ret;
1384 int n;
1385
1386 /* We need to remove some clues. We'll do this by forming a list of all
1387 * available clues, shuffling it, then going along one at a
1388 * time clearing each clue in turn for which doing so doesn't render the
1389 * board unsolvable. */
1390 face_list = snewn(num_faces, int);
1391 for (n = 0; n < num_faces; ++n) {
1392 face_list[n] = n;
1393 }
1394
1395 shuffle(face_list, num_faces, sizeof(int), rs);
1396
1397 for (n = 0; n < num_faces; ++n) {
1398 saved_ret = dup_game(ret);
1399 ret->clues[face_list[n]] = -1;
1400
1401 if (game_has_unique_soln(ret, diff)) {
1402 free_game(saved_ret);
1403 } else {
1404 free_game(ret);
1405 ret = saved_ret;
1406 }
1407 }
1408 sfree(face_list);
1409
1410 return ret;
1411}
1412
1413
1414static char *new_game_desc(const game_params *params, random_state *rs,
1415 char **aux, int interactive)
1416{
1417 /* solution and description both use run-length encoding in obvious ways */
1418 char *retval, *game_desc, *grid_desc;
1419 grid *g;
1420 game_state *state = snew(game_state);
1421 game_state *state_new;
1422
1423 grid_desc = grid_new_desc(grid_types[params->type], params->w, params->h, rs);
1424 state->game_grid = g = loopy_generate_grid(params, grid_desc);
1425
1426 state->clues = snewn(g->num_faces, signed char);
1427 state->lines = snewn(g->num_edges, char);
1428 state->line_errors = snewn(g->num_edges, unsigned char);
1429 state->exactly_one_loop = FALSE;
1430
1431 state->grid_type = params->type;
1432
1433 newboard_please:
1434
1435 memset(state->lines, LINE_UNKNOWN, g->num_edges);
1436 memset(state->line_errors, 0, g->num_edges);
1437
1438 state->solved = state->cheated = FALSE;
1439
1440 /* Get a new random solvable board with all its clues filled in. Yes, this
1441 * can loop for ever if the params are suitably unfavourable, but
1442 * preventing games smaller than 4x4 seems to stop this happening */
1443 do {
1444 add_full_clues(state, rs);
1445 } while (!game_has_unique_soln(state, params->diff));
1446
1447 state_new = remove_clues(state, rs, params->diff);
1448 free_game(state);
1449 state = state_new;
1450
1451
1452 if (params->diff > 0 && game_has_unique_soln(state, params->diff-1)) {
1453#ifdef SHOW_WORKING
1454 fprintf(stderr, "Rejecting board, it is too easy\n");
1455#endif
1456 goto newboard_please;
1457 }
1458
1459 game_desc = state_to_text(state);
1460
1461 free_game(state);
1462
1463 if (grid_desc) {
1464 retval = snewn(strlen(grid_desc) + 1 + strlen(game_desc) + 1, char);
1465 sprintf(retval, "%s%c%s", grid_desc, (int)GRID_DESC_SEP, game_desc);
1466 sfree(grid_desc);
1467 sfree(game_desc);
1468 } else {
1469 retval = game_desc;
1470 }
1471
1472 assert(!validate_desc(params, retval));
1473
1474 return retval;
1475}
1476
1477static game_state *new_game(midend *me, const game_params *params,
1478 const char *desc)
1479{
1480 int i;
1481 game_state *state = snew(game_state);
1482 int empties_to_make = 0;
1483 int n,n2;
1484 const char *dp;
1485 char *grid_desc;
1486 grid *g;
1487 int num_faces, num_edges;
1488
1489 grid_desc = extract_grid_desc(&desc);
1490 state->game_grid = g = loopy_generate_grid(params, grid_desc);
1491 if (grid_desc) sfree(grid_desc);
1492
1493 dp = desc;
1494
1495 num_faces = g->num_faces;
1496 num_edges = g->num_edges;
1497
1498 state->clues = snewn(num_faces, signed char);
1499 state->lines = snewn(num_edges, char);
1500 state->line_errors = snewn(num_edges, unsigned char);
1501 state->exactly_one_loop = FALSE;
1502
1503 state->solved = state->cheated = FALSE;
1504
1505 state->grid_type = params->type;
1506
1507 for (i = 0; i < num_faces; i++) {
1508 if (empties_to_make) {
1509 empties_to_make--;
1510 state->clues[i] = -1;
1511 continue;
1512 }
1513
1514 assert(*dp);
1515 n = *dp - '0';
1516 n2 = *dp - 'A' + 10;
1517 if (n >= 0 && n < 10) {
1518 state->clues[i] = n;
1519 } else if (n2 >= 10 && n2 < 36) {
1520 state->clues[i] = n2;
1521 } else {
1522 n = *dp - 'a' + 1;
1523 assert(n > 0);
1524 state->clues[i] = -1;
1525 empties_to_make = n - 1;
1526 }
1527 ++dp;
1528 }
1529
1530 memset(state->lines, LINE_UNKNOWN, num_edges);
1531 memset(state->line_errors, 0, num_edges);
1532 return state;
1533}
1534
1535/* Calculates the line_errors data, and checks if the current state is a
1536 * solution */
1537static int check_completion(game_state *state)
1538{
1539 grid *g = state->game_grid;
1540 int i, ret;
1541 int *dsf, *component_state;
1542 int nsilly, nloop, npath, largest_comp, largest_size, total_pathsize;
1543 enum { COMP_NONE, COMP_LOOP, COMP_PATH, COMP_SILLY, COMP_EMPTY };
1544
1545 memset(state->line_errors, 0, g->num_edges);
1546
1547 /*
1548 * Find loops in the grid, and determine whether the puzzle is
1549 * solved.
1550 *
1551 * Loopy is a bit more complicated than most puzzles that care
1552 * about loop detection. In most of them, loops are simply
1553 * _forbidden_; so the obviously right way to do
1554 * error-highlighting during play is to light up a graph edge red
1555 * iff it is part of a loop, which is exactly what the centralised
1556 * findloop.c makes easy.
1557 *
1558 * But Loopy is unusual in that you're _supposed_ to be making a
1559 * loop - and yet _some_ loops are not the right loop. So we need
1560 * to be more discriminating, by identifying loops one by one and
1561 * then thinking about which ones to highlight, and so findloop.c
1562 * isn't quite the right tool for the job in this case.
1563 *
1564 * Worse still, consider situations in which the grid contains a
1565 * loop and also some non-loop edges: there are some cases like
1566 * this in which the user's intuitive expectation would be to
1567 * highlight the loop (if you're only about half way through the
1568 * puzzle and have accidentally made a little loop in some corner
1569 * of the grid), and others in which they'd be more likely to
1570 * expect you to highlight the non-loop edges (if you've just
1571 * closed off a whole loop that you thought was the entire
1572 * solution, but forgot some disconnected edges in a corner
1573 * somewhere). So while it's easy enough to check whether the
1574 * solution is _right_, highlighting the wrong parts is a tricky
1575 * problem for this puzzle!
1576 *
1577 * I'd quite like, in some situations, to identify the largest
1578 * loop among the player's YES edges, and then light up everything
1579 * other than that. But finding the longest cycle in a graph is an
1580 * NP-complete problem (because, in particular, it must return a
1581 * Hamilton cycle if one exists).
1582 *
1583 * However, I think we can make the problem tractable by
1584 * exercising the Puzzles principle that it isn't absolutely
1585 * necessary to highlight _all_ errors: the key point is that by
1586 * the time the user has filled in the whole grid, they should
1587 * either have seen a completion flash, or have _some_ error
1588 * highlight showing them why the solution isn't right. So in
1589 * principle it would be *just about* good enough to highlight
1590 * just one error in the whole grid, if there was really no better
1591 * way. But we'd like to highlight as many errors as possible.
1592 *
1593 * In this case, I think the simple approach is to make use of the
1594 * fact that no vertex may have degree > 2, and that's really
1595 * simple to detect. So the plan goes like this:
1596 *
1597 * - Form the dsf of connected components of the graph vertices.
1598 *
1599 * - Highlight an error at any vertex with degree > 2. (It so
1600 * happens that we do this by lighting up all the edges
1601 * incident to that vertex, but that's an output detail.)
1602 *
1603 * - Any component that contains such a vertex is now excluded
1604 * from further consideration, because it already has a
1605 * highlight.
1606 *
1607 * - The remaining components have no vertex with degree > 2, and
1608 * hence they all consist of either a simple loop, or a simple
1609 * path with two endpoints.
1610 *
1611 * - For these purposes, group together all the paths and imagine
1612 * them to be a single component (because in most normal
1613 * situations the player will gradually build up the solution
1614 * _not_ all in one connected segment, but as lots of separate
1615 * little path pieces that gradually connect to each other).
1616 *
1617 * - After doing that, if there is exactly one (sensible)
1618 * component - be it a collection of paths or a loop - then
1619 * highlight no further edge errors. (The former case is normal
1620 * during play, and the latter is a potentially solved puzzle.)
1621 *
1622 * - Otherwise, find the largest of the sensible components,
1623 * leave that one unhighlighted, and light the rest up in red.
1624 */
1625
1626 dsf = snew_dsf(g->num_dots);
1627
1628 /* Build the dsf. */
1629 for (i = 0; i < g->num_edges; i++) {
1630 if (state->lines[i] == LINE_YES) {
1631 grid_edge *e = g->edges + i;
1632 int d1 = e->dot1 - g->dots, d2 = e->dot2 - g->dots;
1633 dsf_merge(dsf, d1, d2);
1634 }
1635 }
1636
1637 /* Initialise a state variable for each connected component. */
1638 component_state = snewn(g->num_dots, int);
1639 for (i = 0; i < g->num_dots; i++) {
1640 if (dsf_canonify(dsf, i) == i)
1641 component_state[i] = COMP_LOOP;
1642 else
1643 component_state[i] = COMP_NONE;
1644 }
1645
1646 /* Check for dots with degree > 3. Here we also spot dots of
1647 * degree 1 in which the user has marked all the non-edges as
1648 * LINE_NO, because those are also clear vertex-level errors, so
1649 * we give them the same treatment of excluding their connected
1650 * component from the subsequent loop analysis. */
1651 for (i = 0; i < g->num_dots; i++) {
1652 int comp = dsf_canonify(dsf, i);
1653 int yes = dot_order(state, i, LINE_YES);
1654 int unknown = dot_order(state, i, LINE_UNKNOWN);
1655 if ((yes == 1 && unknown == 0) || (yes >= 3)) {
1656 /* violation, so mark all YES edges as errors */
1657 grid_dot *d = g->dots + i;
1658 int j;
1659 for (j = 0; j < d->order; j++) {
1660 int e = d->edges[j] - g->edges;
1661 if (state->lines[e] == LINE_YES)
1662 state->line_errors[e] = TRUE;
1663 }
1664 /* And mark this component as not worthy of further
1665 * consideration. */
1666 component_state[comp] = COMP_SILLY;
1667
1668 } else if (yes == 0) {
1669 /* A completely isolated dot must also be excluded it from
1670 * the subsequent loop highlighting pass, but we tag it
1671 * with a different enum value to avoid it counting
1672 * towards the components that inhibit returning a win
1673 * status. */
1674 component_state[comp] = COMP_EMPTY;
1675 } else if (yes == 1) {
1676 /* A dot with degree 1 that didn't fall into the 'clearly
1677 * erroneous' case above indicates that this connected
1678 * component will be a path rather than a loop - unless
1679 * something worse elsewhere in the component has
1680 * classified it as silly. */
1681 if (component_state[comp] != COMP_SILLY)
1682 component_state[comp] = COMP_PATH;
1683 }
1684 }
1685
1686 /* Count up the components. Also, find the largest sensible
1687 * component. (Tie-breaking condition is derived from the order of
1688 * vertices in the grid data structure, which is fairly arbitrary
1689 * but at least stays stable throughout the game.) */
1690 nsilly = nloop = npath = 0;
1691 total_pathsize = 0;
1692 largest_comp = largest_size = -1;
1693 for (i = 0; i < g->num_dots; i++) {
1694 if (component_state[i] == COMP_SILLY) {
1695 nsilly++;
1696 } else if (component_state[i] == COMP_PATH) {
1697 total_pathsize += dsf_size(dsf, i);
1698 npath = 1;
1699 } else if (component_state[i] == COMP_LOOP) {
1700 int this_size;
1701
1702 nloop++;
1703
1704 if ((this_size = dsf_size(dsf, i)) > largest_size) {
1705 largest_comp = i;
1706 largest_size = this_size;
1707 }
1708 }
1709 }
1710 if (largest_size < total_pathsize) {
1711 largest_comp = -1; /* means the paths */
1712 largest_size = total_pathsize;
1713 }
1714
1715 if (nloop > 0 && nloop + npath > 1) {
1716 /*
1717 * If there are at least two sensible components including at
1718 * least one loop, highlight all edges in every sensible
1719 * component that is not the largest one.
1720 */
1721 for (i = 0; i < g->num_edges; i++) {
1722 if (state->lines[i] == LINE_YES) {
1723 grid_edge *e = g->edges + i;
1724 int d1 = e->dot1 - g->dots; /* either endpoint is good enough */
1725 int comp = dsf_canonify(dsf, d1);
1726 if ((component_state[comp] == COMP_PATH &&
1727 -1 != largest_comp) ||
1728 (component_state[comp] == COMP_LOOP &&
1729 comp != largest_comp))
1730 state->line_errors[i] = TRUE;
1731 }
1732 }
1733 }
1734
1735 if (nloop == 1 && npath == 0 && nsilly == 0) {
1736 /*
1737 * If there is exactly one component and it is a loop, then
1738 * the puzzle is potentially complete, so check the clues.
1739 */
1740 ret = TRUE;
1741
1742 for (i = 0; i < g->num_faces; i++) {
1743 int c = state->clues[i];
1744 if (c >= 0 && face_order(state, i, LINE_YES) != c) {
1745 ret = FALSE;
1746 break;
1747 }
1748 }
1749
1750 /*
1751 * Also, whether or not the puzzle is actually complete, set
1752 * the flag that says this game_state has exactly one loop and
1753 * nothing else, which will be used to vary the semantics of
1754 * clue highlighting at display time.
1755 */
1756 state->exactly_one_loop = TRUE;
1757 } else {
1758 ret = FALSE;
1759 state->exactly_one_loop = FALSE;
1760 }
1761
1762 sfree(component_state);
1763 sfree(dsf);
1764
1765 return ret;
1766}
1767
1768/* ----------------------------------------------------------------------
1769 * Solver logic
1770 *
1771 * Our solver modes operate as follows. Each mode also uses the modes above it.
1772 *
1773 * Easy Mode
1774 * Just implement the rules of the game.
1775 *
1776 * Normal and Tricky Modes
1777 * For each (adjacent) pair of lines through each dot we store a bit for
1778 * whether at least one of them is on and whether at most one is on. (If we
1779 * know both or neither is on that's already stored more directly.)
1780 *
1781 * Advanced Mode
1782 * Use edsf data structure to make equivalence classes of lines that are
1783 * known identical to or opposite to one another.
1784 */
1785
1786
1787/* DLines:
1788 * For general grids, we consider "dlines" to be pairs of lines joined
1789 * at a dot. The lines must be adjacent around the dot, so we can think of
1790 * a dline as being a dot+face combination. Or, a dot+edge combination where
1791 * the second edge is taken to be the next clockwise edge from the dot.
1792 * Original loopy code didn't have this extra restriction of the lines being
1793 * adjacent. From my tests with square grids, this extra restriction seems to
1794 * take little, if anything, away from the quality of the puzzles.
1795 * A dline can be uniquely identified by an edge/dot combination, given that
1796 * a dline-pair always goes clockwise around its common dot. The edge/dot
1797 * combination can be represented by an edge/bool combination - if bool is
1798 * TRUE, use edge->dot1 else use edge->dot2. So the total number of dlines is
1799 * exactly twice the number of edges in the grid - although the dlines
1800 * spanning the infinite face are not all that useful to the solver.
1801 * Note that, by convention, a dline goes clockwise around its common dot,
1802 * which means the dline goes anti-clockwise around its common face.
1803 */
1804
1805/* Helper functions for obtaining an index into an array of dlines, given
1806 * various information. We assume the grid layout conventions about how
1807 * the various lists are interleaved - see grid_make_consistent() for
1808 * details. */
1809
1810/* i points to the first edge of the dline pair, reading clockwise around
1811 * the dot. */
1812static int dline_index_from_dot(grid *g, grid_dot *d, int i)
1813{
1814 grid_edge *e = d->edges[i];
1815 int ret;
1816#ifdef DEBUG_DLINES
1817 grid_edge *e2;
1818 int i2 = i+1;
1819 if (i2 == d->order) i2 = 0;
1820 e2 = d->edges[i2];
1821#endif
1822 ret = 2 * (e - g->edges) + ((e->dot1 == d) ? 1 : 0);
1823#ifdef DEBUG_DLINES
1824 printf("dline_index_from_dot: d=%d,i=%d, edges [%d,%d] - %d\n",
1825 (int)(d - g->dots), i, (int)(e - g->edges),
1826 (int)(e2 - g->edges), ret);
1827#endif
1828 return ret;
1829}
1830/* i points to the second edge of the dline pair, reading clockwise around
1831 * the face. That is, the edges of the dline, starting at edge{i}, read
1832 * anti-clockwise around the face. By layout conventions, the common dot
1833 * of the dline will be f->dots[i] */
1834static int dline_index_from_face(grid *g, grid_face *f, int i)
1835{
1836 grid_edge *e = f->edges[i];
1837 grid_dot *d = f->dots[i];
1838 int ret;
1839#ifdef DEBUG_DLINES
1840 grid_edge *e2;
1841 int i2 = i - 1;
1842 if (i2 < 0) i2 += f->order;
1843 e2 = f->edges[i2];
1844#endif
1845 ret = 2 * (e - g->edges) + ((e->dot1 == d) ? 1 : 0);
1846#ifdef DEBUG_DLINES
1847 printf("dline_index_from_face: f=%d,i=%d, edges [%d,%d] - %d\n",
1848 (int)(f - g->faces), i, (int)(e - g->edges),
1849 (int)(e2 - g->edges), ret);
1850#endif
1851 return ret;
1852}
1853static int is_atleastone(const char *dline_array, int index)
1854{
1855 return BIT_SET(dline_array[index], 0);
1856}
1857static int set_atleastone(char *dline_array, int index)
1858{
1859 return SET_BIT(dline_array[index], 0);
1860}
1861static int is_atmostone(const char *dline_array, int index)
1862{
1863 return BIT_SET(dline_array[index], 1);
1864}
1865static int set_atmostone(char *dline_array, int index)
1866{
1867 return SET_BIT(dline_array[index], 1);
1868}
1869
1870static void array_setall(char *array, char from, char to, int len)
1871{
1872 char *p = array, *p_old = p;
1873 int len_remaining = len;
1874
1875 while ((p = memchr(p, from, len_remaining))) {
1876 *p = to;
1877 len_remaining -= p - p_old;
1878 p_old = p;
1879 }
1880}
1881
1882/* Helper, called when doing dline dot deductions, in the case where we
1883 * have 4 UNKNOWNs, and two of them (adjacent) have *exactly* one YES between
1884 * them (because of dline atmostone/atleastone).
1885 * On entry, edge points to the first of these two UNKNOWNs. This function
1886 * will find the opposite UNKNOWNS (if they are adjacent to one another)
1887 * and set their corresponding dline to atleastone. (Setting atmostone
1888 * already happens in earlier dline deductions) */
1889static int dline_set_opp_atleastone(solver_state *sstate,
1890 grid_dot *d, int edge)
1891{
1892 game_state *state = sstate->state;
1893 grid *g = state->game_grid;
1894 int N = d->order;
1895 int opp, opp2;
1896 for (opp = 0; opp < N; opp++) {
1897 int opp_dline_index;
1898 if (opp == edge || opp == edge+1 || opp == edge-1)
1899 continue;
1900 if (opp == 0 && edge == N-1)
1901 continue;
1902 if (opp == N-1 && edge == 0)
1903 continue;
1904 opp2 = opp + 1;
1905 if (opp2 == N) opp2 = 0;
1906 /* Check if opp, opp2 point to LINE_UNKNOWNs */
1907 if (state->lines[d->edges[opp] - g->edges] != LINE_UNKNOWN)
1908 continue;
1909 if (state->lines[d->edges[opp2] - g->edges] != LINE_UNKNOWN)
1910 continue;
1911 /* Found opposite UNKNOWNS and they're next to each other */
1912 opp_dline_index = dline_index_from_dot(g, d, opp);
1913 return set_atleastone(sstate->dlines, opp_dline_index);
1914 }
1915 return FALSE;
1916}
1917
1918
1919/* Set pairs of lines around this face which are known to be identical, to
1920 * the given line_state */
1921static int face_setall_identical(solver_state *sstate, int face_index,
1922 enum line_state line_new)
1923{
1924 /* can[dir] contains the canonical line associated with the line in
1925 * direction dir from the square in question. Similarly inv[dir] is
1926 * whether or not the line in question is inverse to its canonical
1927 * element. */
1928 int retval = FALSE;
1929 game_state *state = sstate->state;
1930 grid *g = state->game_grid;
1931 grid_face *f = g->faces + face_index;
1932 int N = f->order;
1933 int i, j;
1934 int can1, can2, inv1, inv2;
1935
1936 for (i = 0; i < N; i++) {
1937 int line1_index = f->edges[i] - g->edges;
1938 if (state->lines[line1_index] != LINE_UNKNOWN)
1939 continue;
1940 for (j = i + 1; j < N; j++) {
1941 int line2_index = f->edges[j] - g->edges;
1942 if (state->lines[line2_index] != LINE_UNKNOWN)
1943 continue;
1944
1945 /* Found two UNKNOWNS */
1946 can1 = edsf_canonify(sstate->linedsf, line1_index, &inv1);
1947 can2 = edsf_canonify(sstate->linedsf, line2_index, &inv2);
1948 if (can1 == can2 && inv1 == inv2) {
1949 solver_set_line(sstate, line1_index, line_new);
1950 solver_set_line(sstate, line2_index, line_new);
1951 }
1952 }
1953 }
1954 return retval;
1955}
1956
1957/* Given a dot or face, and a count of LINE_UNKNOWNs, find them and
1958 * return the edge indices into e. */
1959static void find_unknowns(game_state *state,
1960 grid_edge **edge_list, /* Edge list to search (from a face or a dot) */
1961 int expected_count, /* Number of UNKNOWNs (comes from solver's cache) */
1962 int *e /* Returned edge indices */)
1963{
1964 int c = 0;
1965 grid *g = state->game_grid;
1966 while (c < expected_count) {
1967 int line_index = *edge_list - g->edges;
1968 if (state->lines[line_index] == LINE_UNKNOWN) {
1969 e[c] = line_index;
1970 c++;
1971 }
1972 ++edge_list;
1973 }
1974}
1975
1976/* If we have a list of edges, and we know whether the number of YESs should
1977 * be odd or even, and there are only a few UNKNOWNs, we can do some simple
1978 * linedsf deductions. This can be used for both face and dot deductions.
1979 * Returns the difficulty level of the next solver that should be used,
1980 * or DIFF_MAX if no progress was made. */
1981static int parity_deductions(solver_state *sstate,
1982 grid_edge **edge_list, /* Edge list (from a face or a dot) */
1983 int total_parity, /* Expected number of YESs modulo 2 (either 0 or 1) */
1984 int unknown_count)
1985{
1986 game_state *state = sstate->state;
1987 int diff = DIFF_MAX;
1988 int *linedsf = sstate->linedsf;
1989
1990 if (unknown_count == 2) {
1991 /* Lines are known alike/opposite, depending on inv. */
1992 int e[2];
1993 find_unknowns(state, edge_list, 2, e);
1994 if (merge_lines(sstate, e[0], e[1], total_parity))
1995 diff = min(diff, DIFF_HARD);
1996 } else if (unknown_count == 3) {
1997 int e[3];
1998 int can[3]; /* canonical edges */
1999 int inv[3]; /* whether can[x] is inverse to e[x] */
2000 find_unknowns(state, edge_list, 3, e);
2001 can[0] = edsf_canonify(linedsf, e[0], inv);
2002 can[1] = edsf_canonify(linedsf, e[1], inv+1);
2003 can[2] = edsf_canonify(linedsf, e[2], inv+2);
2004 if (can[0] == can[1]) {
2005 if (solver_set_line(sstate, e[2], (total_parity^inv[0]^inv[1]) ?
2006 LINE_YES : LINE_NO))
2007 diff = min(diff, DIFF_EASY);
2008 }
2009 if (can[0] == can[2]) {
2010 if (solver_set_line(sstate, e[1], (total_parity^inv[0]^inv[2]) ?
2011 LINE_YES : LINE_NO))
2012 diff = min(diff, DIFF_EASY);
2013 }
2014 if (can[1] == can[2]) {
2015 if (solver_set_line(sstate, e[0], (total_parity^inv[1]^inv[2]) ?
2016 LINE_YES : LINE_NO))
2017 diff = min(diff, DIFF_EASY);
2018 }
2019 } else if (unknown_count == 4) {
2020 int e[4];
2021 int can[4]; /* canonical edges */
2022 int inv[4]; /* whether can[x] is inverse to e[x] */
2023 find_unknowns(state, edge_list, 4, e);
2024 can[0] = edsf_canonify(linedsf, e[0], inv);
2025 can[1] = edsf_canonify(linedsf, e[1], inv+1);
2026 can[2] = edsf_canonify(linedsf, e[2], inv+2);
2027 can[3] = edsf_canonify(linedsf, e[3], inv+3);
2028 if (can[0] == can[1]) {
2029 if (merge_lines(sstate, e[2], e[3], total_parity^inv[0]^inv[1]))
2030 diff = min(diff, DIFF_HARD);
2031 } else if (can[0] == can[2]) {
2032 if (merge_lines(sstate, e[1], e[3], total_parity^inv[0]^inv[2]))
2033 diff = min(diff, DIFF_HARD);
2034 } else if (can[0] == can[3]) {
2035 if (merge_lines(sstate, e[1], e[2], total_parity^inv[0]^inv[3]))
2036 diff = min(diff, DIFF_HARD);
2037 } else if (can[1] == can[2]) {
2038 if (merge_lines(sstate, e[0], e[3], total_parity^inv[1]^inv[2]))
2039 diff = min(diff, DIFF_HARD);
2040 } else if (can[1] == can[3]) {
2041 if (merge_lines(sstate, e[0], e[2], total_parity^inv[1]^inv[3]))
2042 diff = min(diff, DIFF_HARD);
2043 } else if (can[2] == can[3]) {
2044 if (merge_lines(sstate, e[0], e[1], total_parity^inv[2]^inv[3]))
2045 diff = min(diff, DIFF_HARD);
2046 }
2047 }
2048 return diff;
2049}
2050
2051
2052/*
2053 * These are the main solver functions.
2054 *
2055 * Their return values are diff values corresponding to the lowest mode solver
2056 * that would notice the work that they have done. For example if the normal
2057 * mode solver adds actual lines or crosses, it will return DIFF_EASY as the
2058 * easy mode solver might be able to make progress using that. It doesn't make
2059 * sense for one of them to return a diff value higher than that of the
2060 * function itself.
2061 *
2062 * Each function returns the lowest value it can, as early as possible, in
2063 * order to try and pass as much work as possible back to the lower level
2064 * solvers which progress more quickly.
2065 */
2066
2067/* PROPOSED NEW DESIGN:
2068 * We have a work queue consisting of 'events' notifying us that something has
2069 * happened that a particular solver mode might be interested in. For example
2070 * the hard mode solver might do something that helps the normal mode solver at
2071 * dot [x,y] in which case it will enqueue an event recording this fact. Then
2072 * we pull events off the work queue, and hand each in turn to the solver that
2073 * is interested in them. If a solver reports that it failed we pass the same
2074 * event on to progressively more advanced solvers and the loop detector. Once
2075 * we've exhausted an event, or it has helped us progress, we drop it and
2076 * continue to the next one. The events are sorted first in order of solver
2077 * complexity (easy first) then order of insertion (oldest first).
2078 * Once we run out of events we loop over each permitted solver in turn
2079 * (easiest first) until either a deduction is made (and an event therefore
2080 * emerges) or no further deductions can be made (in which case we've failed).
2081 *
2082 * QUESTIONS:
2083 * * How do we 'loop over' a solver when both dots and squares are concerned.
2084 * Answer: first all squares then all dots.
2085 */
2086
2087static int trivial_deductions(solver_state *sstate)
2088{
2089 int i, current_yes, current_no;
2090 game_state *state = sstate->state;
2091 grid *g = state->game_grid;
2092 int diff = DIFF_MAX;
2093
2094 /* Per-face deductions */
2095 for (i = 0; i < g->num_faces; i++) {
2096 grid_face *f = g->faces + i;
2097
2098 if (sstate->face_solved[i])
2099 continue;
2100
2101 current_yes = sstate->face_yes_count[i];
2102 current_no = sstate->face_no_count[i];
2103
2104 if (current_yes + current_no == f->order) {
2105 sstate->face_solved[i] = TRUE;
2106 continue;
2107 }
2108
2109 if (state->clues[i] < 0)
2110 continue;
2111
2112 /*
2113 * This code checks whether the numeric clue on a face is so
2114 * large as to permit all its remaining LINE_UNKNOWNs to be
2115 * filled in as LINE_YES, or alternatively so small as to
2116 * permit them all to be filled in as LINE_NO.
2117 */
2118
2119 if (state->clues[i] < current_yes) {
2120 sstate->solver_status = SOLVER_MISTAKE;
2121 return DIFF_EASY;
2122 }
2123 if (state->clues[i] == current_yes) {
2124 if (face_setall(sstate, i, LINE_UNKNOWN, LINE_NO))
2125 diff = min(diff, DIFF_EASY);
2126 sstate->face_solved[i] = TRUE;
2127 continue;
2128 }
2129
2130 if (f->order - state->clues[i] < current_no) {
2131 sstate->solver_status = SOLVER_MISTAKE;
2132 return DIFF_EASY;
2133 }
2134 if (f->order - state->clues[i] == current_no) {
2135 if (face_setall(sstate, i, LINE_UNKNOWN, LINE_YES))
2136 diff = min(diff, DIFF_EASY);
2137 sstate->face_solved[i] = TRUE;
2138 continue;
2139 }
2140
2141 if (f->order - state->clues[i] == current_no + 1 &&
2142 f->order - current_yes - current_no > 2) {
2143 /*
2144 * One small refinement to the above: we also look for any
2145 * adjacent pair of LINE_UNKNOWNs around the face with
2146 * some LINE_YES incident on it from elsewhere. If we find
2147 * one, then we know that pair of LINE_UNKNOWNs can't
2148 * _both_ be LINE_YES, and hence that pushes us one line
2149 * closer to being able to determine all the rest.
2150 */
2151 int j, k, e1, e2, e, d;
2152
2153 for (j = 0; j < f->order; j++) {
2154 e1 = f->edges[j] - g->edges;
2155 e2 = f->edges[j+1 < f->order ? j+1 : 0] - g->edges;
2156
2157 if (g->edges[e1].dot1 == g->edges[e2].dot1 ||
2158 g->edges[e1].dot1 == g->edges[e2].dot2) {
2159 d = g->edges[e1].dot1 - g->dots;
2160 } else {
2161 assert(g->edges[e1].dot2 == g->edges[e2].dot1 ||
2162 g->edges[e1].dot2 == g->edges[e2].dot2);
2163 d = g->edges[e1].dot2 - g->dots;
2164 }
2165
2166 if (state->lines[e1] == LINE_UNKNOWN &&
2167 state->lines[e2] == LINE_UNKNOWN) {
2168 for (k = 0; k < g->dots[d].order; k++) {
2169 int e = g->dots[d].edges[k] - g->edges;
2170 if (state->lines[e] == LINE_YES)
2171 goto found; /* multi-level break */
2172 }
2173 }
2174 }
2175 continue;
2176
2177 found:
2178 /*
2179 * If we get here, we've found such a pair of edges, and
2180 * they're e1 and e2.
2181 */
2182 for (j = 0; j < f->order; j++) {
2183 e = f->edges[j] - g->edges;
2184 if (state->lines[e] == LINE_UNKNOWN && e != e1 && e != e2) {
2185 int r = solver_set_line(sstate, e, LINE_YES);
2186 assert(r);
2187 diff = min(diff, DIFF_EASY);
2188 }
2189 }
2190 }
2191 }
2192
2193 check_caches(sstate);
2194
2195 /* Per-dot deductions */
2196 for (i = 0; i < g->num_dots; i++) {
2197 grid_dot *d = g->dots + i;
2198 int yes, no, unknown;
2199
2200 if (sstate->dot_solved[i])
2201 continue;
2202
2203 yes = sstate->dot_yes_count[i];
2204 no = sstate->dot_no_count[i];
2205 unknown = d->order - yes - no;
2206
2207 if (yes == 0) {
2208 if (unknown == 0) {
2209 sstate->dot_solved[i] = TRUE;
2210 } else if (unknown == 1) {
2211 dot_setall(sstate, i, LINE_UNKNOWN, LINE_NO);
2212 diff = min(diff, DIFF_EASY);
2213 sstate->dot_solved[i] = TRUE;
2214 }
2215 } else if (yes == 1) {
2216 if (unknown == 0) {
2217 sstate->solver_status = SOLVER_MISTAKE;
2218 return DIFF_EASY;
2219 } else if (unknown == 1) {
2220 dot_setall(sstate, i, LINE_UNKNOWN, LINE_YES);
2221 diff = min(diff, DIFF_EASY);
2222 }
2223 } else if (yes == 2) {
2224 if (unknown > 0) {
2225 dot_setall(sstate, i, LINE_UNKNOWN, LINE_NO);
2226 diff = min(diff, DIFF_EASY);
2227 }
2228 sstate->dot_solved[i] = TRUE;
2229 } else {
2230 sstate->solver_status = SOLVER_MISTAKE;
2231 return DIFF_EASY;
2232 }
2233 }
2234
2235 check_caches(sstate);
2236
2237 return diff;
2238}
2239
2240static int dline_deductions(solver_state *sstate)
2241{
2242 game_state *state = sstate->state;
2243 grid *g = state->game_grid;
2244 char *dlines = sstate->dlines;
2245 int i;
2246 int diff = DIFF_MAX;
2247
2248 /* ------ Face deductions ------ */
2249
2250 /* Given a set of dline atmostone/atleastone constraints, need to figure
2251 * out if we can deduce any further info. For more general faces than
2252 * squares, this turns out to be a tricky problem.
2253 * The approach taken here is to define (per face) NxN matrices:
2254 * "maxs" and "mins".
2255 * The entries maxs(j,k) and mins(j,k) define the upper and lower limits
2256 * for the possible number of edges that are YES between positions j and k
2257 * going clockwise around the face. Can think of j and k as marking dots
2258 * around the face (recall the labelling scheme: edge0 joins dot0 to dot1,
2259 * edge1 joins dot1 to dot2 etc).
2260 * Trivially, mins(j,j) = maxs(j,j) = 0, and we don't even bother storing
2261 * these. mins(j,j+1) and maxs(j,j+1) are determined by whether edge{j}
2262 * is YES, NO or UNKNOWN. mins(j,j+2) and maxs(j,j+2) are related to
2263 * the dline atmostone/atleastone status for edges j and j+1.
2264 *
2265 * Then we calculate the remaining entries recursively. We definitely
2266 * know that
2267 * mins(j,k) >= { mins(j,u) + mins(u,k) } for any u between j and k.
2268 * This is because any valid placement of YESs between j and k must give
2269 * a valid placement between j and u, and also between u and k.
2270 * I believe it's sufficient to use just the two values of u:
2271 * j+1 and j+2. Seems to work well in practice - the bounds we compute
2272 * are rigorous, even if they might not be best-possible.
2273 *
2274 * Once we have maxs and mins calculated, we can make inferences about
2275 * each dline{j,j+1} by looking at the possible complementary edge-counts
2276 * mins(j+2,j) and maxs(j+2,j) and comparing these with the face clue.
2277 * As well as dlines, we can make similar inferences about single edges.
2278 * For example, consider a pentagon with clue 3, and we know at most one
2279 * of (edge0, edge1) is YES, and at most one of (edge2, edge3) is YES.
2280 * We could then deduce edge4 is YES, because maxs(0,4) would be 2, so
2281 * that final edge would have to be YES to make the count up to 3.
2282 */
2283
2284 /* Much quicker to allocate arrays on the stack than the heap, so
2285 * define the largest possible face size, and base our array allocations
2286 * on that. We check this with an assertion, in case someone decides to
2287 * make a grid which has larger faces than this. Note, this algorithm
2288 * could get quite expensive if there are many large faces. */
2289#define MAX_FACE_SIZE 12
2290
2291 for (i = 0; i < g->num_faces; i++) {
2292 int maxs[MAX_FACE_SIZE][MAX_FACE_SIZE];
2293 int mins[MAX_FACE_SIZE][MAX_FACE_SIZE];
2294 grid_face *f = g->faces + i;
2295 int N = f->order;
2296 int j,m;
2297 int clue = state->clues[i];
2298 assert(N <= MAX_FACE_SIZE);
2299 if (sstate->face_solved[i])
2300 continue;
2301 if (clue < 0) continue;
2302
2303 /* Calculate the (j,j+1) entries */
2304 for (j = 0; j < N; j++) {
2305 int edge_index = f->edges[j] - g->edges;
2306 int dline_index;
2307 enum line_state line1 = state->lines[edge_index];
2308 enum line_state line2;
2309 int tmp;
2310 int k = j + 1;
2311 if (k >= N) k = 0;
2312 maxs[j][k] = (line1 == LINE_NO) ? 0 : 1;
2313 mins[j][k] = (line1 == LINE_YES) ? 1 : 0;
2314 /* Calculate the (j,j+2) entries */
2315 dline_index = dline_index_from_face(g, f, k);
2316 edge_index = f->edges[k] - g->edges;
2317 line2 = state->lines[edge_index];
2318 k++;
2319 if (k >= N) k = 0;
2320
2321 /* max */
2322 tmp = 2;
2323 if (line1 == LINE_NO) tmp--;
2324 if (line2 == LINE_NO) tmp--;
2325 if (tmp == 2 && is_atmostone(dlines, dline_index))
2326 tmp = 1;
2327 maxs[j][k] = tmp;
2328
2329 /* min */
2330 tmp = 0;
2331 if (line1 == LINE_YES) tmp++;
2332 if (line2 == LINE_YES) tmp++;
2333 if (tmp == 0 && is_atleastone(dlines, dline_index))
2334 tmp = 1;
2335 mins[j][k] = tmp;
2336 }
2337
2338 /* Calculate the (j,j+m) entries for m between 3 and N-1 */
2339 for (m = 3; m < N; m++) {
2340 for (j = 0; j < N; j++) {
2341 int k = j + m;
2342 int u = j + 1;
2343 int v = j + 2;
2344 int tmp;
2345 if (k >= N) k -= N;
2346 if (u >= N) u -= N;
2347 if (v >= N) v -= N;
2348 maxs[j][k] = maxs[j][u] + maxs[u][k];
2349 mins[j][k] = mins[j][u] + mins[u][k];
2350 tmp = maxs[j][v] + maxs[v][k];
2351 maxs[j][k] = min(maxs[j][k], tmp);
2352 tmp = mins[j][v] + mins[v][k];
2353 mins[j][k] = max(mins[j][k], tmp);
2354 }
2355 }
2356
2357 /* See if we can make any deductions */
2358 for (j = 0; j < N; j++) {
2359 int k;
2360 grid_edge *e = f->edges[j];
2361 int line_index = e - g->edges;
2362 int dline_index;
2363
2364 if (state->lines[line_index] != LINE_UNKNOWN)
2365 continue;
2366 k = j + 1;
2367 if (k >= N) k = 0;
2368
2369 /* minimum YESs in the complement of this edge */
2370 if (mins[k][j] > clue) {
2371 sstate->solver_status = SOLVER_MISTAKE;
2372 return DIFF_EASY;
2373 }
2374 if (mins[k][j] == clue) {
2375 /* setting this edge to YES would make at least
2376 * (clue+1) edges - contradiction */
2377 solver_set_line(sstate, line_index, LINE_NO);
2378 diff = min(diff, DIFF_EASY);
2379 }
2380 if (maxs[k][j] < clue - 1) {
2381 sstate->solver_status = SOLVER_MISTAKE;
2382 return DIFF_EASY;
2383 }
2384 if (maxs[k][j] == clue - 1) {
2385 /* Only way to satisfy the clue is to set edge{j} as YES */
2386 solver_set_line(sstate, line_index, LINE_YES);
2387 diff = min(diff, DIFF_EASY);
2388 }
2389
2390 /* More advanced deduction that allows propagation along diagonal
2391 * chains of faces connected by dots, for example, 3-2-...-2-3
2392 * in square grids. */
2393 if (sstate->diff >= DIFF_TRICKY) {
2394 /* Now see if we can make dline deduction for edges{j,j+1} */
2395 e = f->edges[k];
2396 if (state->lines[e - g->edges] != LINE_UNKNOWN)
2397 /* Only worth doing this for an UNKNOWN,UNKNOWN pair.
2398 * Dlines where one of the edges is known, are handled in the
2399 * dot-deductions */
2400 continue;
2401
2402 dline_index = dline_index_from_face(g, f, k);
2403 k++;
2404 if (k >= N) k = 0;
2405
2406 /* minimum YESs in the complement of this dline */
2407 if (mins[k][j] > clue - 2) {
2408 /* Adding 2 YESs would break the clue */
2409 if (set_atmostone(dlines, dline_index))
2410 diff = min(diff, DIFF_NORMAL);
2411 }
2412 /* maximum YESs in the complement of this dline */
2413 if (maxs[k][j] < clue) {
2414 /* Adding 2 NOs would mean not enough YESs */
2415 if (set_atleastone(dlines, dline_index))
2416 diff = min(diff, DIFF_NORMAL);
2417 }
2418 }
2419 }
2420 }
2421
2422 if (diff < DIFF_NORMAL)
2423 return diff;
2424
2425 /* ------ Dot deductions ------ */
2426
2427 for (i = 0; i < g->num_dots; i++) {
2428 grid_dot *d = g->dots + i;
2429 int N = d->order;
2430 int yes, no, unknown;
2431 int j;
2432 if (sstate->dot_solved[i])
2433 continue;
2434 yes = sstate->dot_yes_count[i];
2435 no = sstate->dot_no_count[i];
2436 unknown = N - yes - no;
2437
2438 for (j = 0; j < N; j++) {
2439 int k;
2440 int dline_index;
2441 int line1_index, line2_index;
2442 enum line_state line1, line2;
2443 k = j + 1;
2444 if (k >= N) k = 0;
2445 dline_index = dline_index_from_dot(g, d, j);
2446 line1_index = d->edges[j] - g->edges;
2447 line2_index = d->edges[k] - g->edges;
2448 line1 = state->lines[line1_index];
2449 line2 = state->lines[line2_index];
2450
2451 /* Infer dline state from line state */
2452 if (line1 == LINE_NO || line2 == LINE_NO) {
2453 if (set_atmostone(dlines, dline_index))
2454 diff = min(diff, DIFF_NORMAL);
2455 }
2456 if (line1 == LINE_YES || line2 == LINE_YES) {
2457 if (set_atleastone(dlines, dline_index))
2458 diff = min(diff, DIFF_NORMAL);
2459 }
2460 /* Infer line state from dline state */
2461 if (is_atmostone(dlines, dline_index)) {
2462 if (line1 == LINE_YES && line2 == LINE_UNKNOWN) {
2463 solver_set_line(sstate, line2_index, LINE_NO);
2464 diff = min(diff, DIFF_EASY);
2465 }
2466 if (line2 == LINE_YES && line1 == LINE_UNKNOWN) {
2467 solver_set_line(sstate, line1_index, LINE_NO);
2468 diff = min(diff, DIFF_EASY);
2469 }
2470 }
2471 if (is_atleastone(dlines, dline_index)) {
2472 if (line1 == LINE_NO && line2 == LINE_UNKNOWN) {
2473 solver_set_line(sstate, line2_index, LINE_YES);
2474 diff = min(diff, DIFF_EASY);
2475 }
2476 if (line2 == LINE_NO && line1 == LINE_UNKNOWN) {
2477 solver_set_line(sstate, line1_index, LINE_YES);
2478 diff = min(diff, DIFF_EASY);
2479 }
2480 }
2481 /* Deductions that depend on the numbers of lines.
2482 * Only bother if both lines are UNKNOWN, otherwise the
2483 * easy-mode solver (or deductions above) would have taken
2484 * care of it. */
2485 if (line1 != LINE_UNKNOWN || line2 != LINE_UNKNOWN)
2486 continue;
2487
2488 if (yes == 0 && unknown == 2) {
2489 /* Both these unknowns must be identical. If we know
2490 * atmostone or atleastone, we can make progress. */
2491 if (is_atmostone(dlines, dline_index)) {
2492 solver_set_line(sstate, line1_index, LINE_NO);
2493 solver_set_line(sstate, line2_index, LINE_NO);
2494 diff = min(diff, DIFF_EASY);
2495 }
2496 if (is_atleastone(dlines, dline_index)) {
2497 solver_set_line(sstate, line1_index, LINE_YES);
2498 solver_set_line(sstate, line2_index, LINE_YES);
2499 diff = min(diff, DIFF_EASY);
2500 }
2501 }
2502 if (yes == 1) {
2503 if (set_atmostone(dlines, dline_index))
2504 diff = min(diff, DIFF_NORMAL);
2505 if (unknown == 2) {
2506 if (set_atleastone(dlines, dline_index))
2507 diff = min(diff, DIFF_NORMAL);
2508 }
2509 }
2510
2511 /* More advanced deduction that allows propagation along diagonal
2512 * chains of faces connected by dots, for example: 3-2-...-2-3
2513 * in square grids. */
2514 if (sstate->diff >= DIFF_TRICKY) {
2515 /* If we have atleastone set for this dline, infer
2516 * atmostone for each "opposite" dline (that is, each
2517 * dline without edges in common with this one).
2518 * Again, this test is only worth doing if both these
2519 * lines are UNKNOWN. For if one of these lines were YES,
2520 * the (yes == 1) test above would kick in instead. */
2521 if (is_atleastone(dlines, dline_index)) {
2522 int opp;
2523 for (opp = 0; opp < N; opp++) {
2524 int opp_dline_index;
2525 if (opp == j || opp == j+1 || opp == j-1)
2526 continue;
2527 if (j == 0 && opp == N-1)
2528 continue;
2529 if (j == N-1 && opp == 0)
2530 continue;
2531 opp_dline_index = dline_index_from_dot(g, d, opp);
2532 if (set_atmostone(dlines, opp_dline_index))
2533 diff = min(diff, DIFF_NORMAL);
2534 }
2535 if (yes == 0 && is_atmostone(dlines, dline_index)) {
2536 /* This dline has *exactly* one YES and there are no
2537 * other YESs. This allows more deductions. */
2538 if (unknown == 3) {
2539 /* Third unknown must be YES */
2540 for (opp = 0; opp < N; opp++) {
2541 int opp_index;
2542 if (opp == j || opp == k)
2543 continue;
2544 opp_index = d->edges[opp] - g->edges;
2545 if (state->lines[opp_index] == LINE_UNKNOWN) {
2546 solver_set_line(sstate, opp_index,
2547 LINE_YES);
2548 diff = min(diff, DIFF_EASY);
2549 }
2550 }
2551 } else if (unknown == 4) {
2552 /* Exactly one of opposite UNKNOWNS is YES. We've
2553 * already set atmostone, so set atleastone as
2554 * well.
2555 */
2556 if (dline_set_opp_atleastone(sstate, d, j))
2557 diff = min(diff, DIFF_NORMAL);
2558 }
2559 }
2560 }
2561 }
2562 }
2563 }
2564 return diff;
2565}
2566
2567static int linedsf_deductions(solver_state *sstate)
2568{
2569 game_state *state = sstate->state;
2570 grid *g = state->game_grid;
2571 char *dlines = sstate->dlines;
2572 int i;
2573 int diff = DIFF_MAX;
2574 int diff_tmp;
2575
2576 /* ------ Face deductions ------ */
2577
2578 /* A fully-general linedsf deduction seems overly complicated
2579 * (I suspect the problem is NP-complete, though in practice it might just
2580 * be doable because faces are limited in size).
2581 * For simplicity, we only consider *pairs* of LINE_UNKNOWNS that are
2582 * known to be identical. If setting them both to YES (or NO) would break
2583 * the clue, set them to NO (or YES). */
2584
2585 for (i = 0; i < g->num_faces; i++) {
2586 int N, yes, no, unknown;
2587 int clue;
2588
2589 if (sstate->face_solved[i])
2590 continue;
2591 clue = state->clues[i];
2592 if (clue < 0)
2593 continue;
2594
2595 N = g->faces[i].order;
2596 yes = sstate->face_yes_count[i];
2597 if (yes + 1 == clue) {
2598 if (face_setall_identical(sstate, i, LINE_NO))
2599 diff = min(diff, DIFF_EASY);
2600 }
2601 no = sstate->face_no_count[i];
2602 if (no + 1 == N - clue) {
2603 if (face_setall_identical(sstate, i, LINE_YES))
2604 diff = min(diff, DIFF_EASY);
2605 }
2606
2607 /* Reload YES count, it might have changed */
2608 yes = sstate->face_yes_count[i];
2609 unknown = N - no - yes;
2610
2611 /* Deductions with small number of LINE_UNKNOWNs, based on overall
2612 * parity of lines. */
2613 diff_tmp = parity_deductions(sstate, g->faces[i].edges,
2614 (clue - yes) % 2, unknown);
2615 diff = min(diff, diff_tmp);
2616 }
2617
2618 /* ------ Dot deductions ------ */
2619 for (i = 0; i < g->num_dots; i++) {
2620 grid_dot *d = g->dots + i;
2621 int N = d->order;
2622 int j;
2623 int yes, no, unknown;
2624 /* Go through dlines, and do any dline<->linedsf deductions wherever
2625 * we find two UNKNOWNS. */
2626 for (j = 0; j < N; j++) {
2627 int dline_index = dline_index_from_dot(g, d, j);
2628 int line1_index;
2629 int line2_index;
2630 int can1, can2, inv1, inv2;
2631 int j2;
2632 line1_index = d->edges[j] - g->edges;
2633 if (state->lines[line1_index] != LINE_UNKNOWN)
2634 continue;
2635 j2 = j + 1;
2636 if (j2 == N) j2 = 0;
2637 line2_index = d->edges[j2] - g->edges;
2638 if (state->lines[line2_index] != LINE_UNKNOWN)
2639 continue;
2640 /* Infer dline flags from linedsf */
2641 can1 = edsf_canonify(sstate->linedsf, line1_index, &inv1);
2642 can2 = edsf_canonify(sstate->linedsf, line2_index, &inv2);
2643 if (can1 == can2 && inv1 != inv2) {
2644 /* These are opposites, so set dline atmostone/atleastone */
2645 if (set_atmostone(dlines, dline_index))
2646 diff = min(diff, DIFF_NORMAL);
2647 if (set_atleastone(dlines, dline_index))
2648 diff = min(diff, DIFF_NORMAL);
2649 continue;
2650 }
2651 /* Infer linedsf from dline flags */
2652 if (is_atmostone(dlines, dline_index)
2653 && is_atleastone(dlines, dline_index)) {
2654 if (merge_lines(sstate, line1_index, line2_index, 1))
2655 diff = min(diff, DIFF_HARD);
2656 }
2657 }
2658
2659 /* Deductions with small number of LINE_UNKNOWNs, based on overall
2660 * parity of lines. */
2661 yes = sstate->dot_yes_count[i];
2662 no = sstate->dot_no_count[i];
2663 unknown = N - yes - no;
2664 diff_tmp = parity_deductions(sstate, d->edges,
2665 yes % 2, unknown);
2666 diff = min(diff, diff_tmp);
2667 }
2668
2669 /* ------ Edge dsf deductions ------ */
2670
2671 /* If the state of a line is known, deduce the state of its canonical line
2672 * too, and vice versa. */
2673 for (i = 0; i < g->num_edges; i++) {
2674 int can, inv;
2675 enum line_state s;
2676 can = edsf_canonify(sstate->linedsf, i, &inv);
2677 if (can == i)
2678 continue;
2679 s = sstate->state->lines[can];
2680 if (s != LINE_UNKNOWN) {
2681 if (solver_set_line(sstate, i, inv ? OPP(s) : s))
2682 diff = min(diff, DIFF_EASY);
2683 } else {
2684 s = sstate->state->lines[i];
2685 if (s != LINE_UNKNOWN) {
2686 if (solver_set_line(sstate, can, inv ? OPP(s) : s))
2687 diff = min(diff, DIFF_EASY);
2688 }
2689 }
2690 }
2691
2692 return diff;
2693}
2694
2695static int loop_deductions(solver_state *sstate)
2696{
2697 int edgecount = 0, clues = 0, satclues = 0, sm1clues = 0;
2698 game_state *state = sstate->state;
2699 grid *g = state->game_grid;
2700 int shortest_chainlen = g->num_dots;
2701 int loop_found = FALSE;
2702 int dots_connected;
2703 int progress = FALSE;
2704 int i;
2705
2706 /*
2707 * Go through the grid and update for all the new edges.
2708 * Since merge_dots() is idempotent, the simplest way to
2709 * do this is just to update for _all_ the edges.
2710 * Also, while we're here, we count the edges.
2711 */
2712 for (i = 0; i < g->num_edges; i++) {
2713 if (state->lines[i] == LINE_YES) {
2714 loop_found |= merge_dots(sstate, i);
2715 edgecount++;
2716 }
2717 }
2718
2719 /*
2720 * Count the clues, count the satisfied clues, and count the
2721 * satisfied-minus-one clues.
2722 */
2723 for (i = 0; i < g->num_faces; i++) {
2724 int c = state->clues[i];
2725 if (c >= 0) {
2726 int o = sstate->face_yes_count[i];
2727 if (o == c)
2728 satclues++;
2729 else if (o == c-1)
2730 sm1clues++;
2731 clues++;
2732 }
2733 }
2734
2735 for (i = 0; i < g->num_dots; ++i) {
2736 dots_connected =
2737 sstate->looplen[dsf_canonify(sstate->dotdsf, i)];
2738 if (dots_connected > 1)
2739 shortest_chainlen = min(shortest_chainlen, dots_connected);
2740 }
2741
2742 assert(sstate->solver_status == SOLVER_INCOMPLETE);
2743
2744 if (satclues == clues && shortest_chainlen == edgecount) {
2745 sstate->solver_status = SOLVER_SOLVED;
2746 /* This discovery clearly counts as progress, even if we haven't
2747 * just added any lines or anything */
2748 progress = TRUE;
2749 goto finished_loop_deductionsing;
2750 }
2751
2752 /*
2753 * Now go through looking for LINE_UNKNOWN edges which
2754 * connect two dots that are already in the same
2755 * equivalence class. If we find one, test to see if the
2756 * loop it would create is a solution.
2757 */
2758 for (i = 0; i < g->num_edges; i++) {
2759 grid_edge *e = g->edges + i;
2760 int d1 = e->dot1 - g->dots;
2761 int d2 = e->dot2 - g->dots;
2762 int eqclass, val;
2763 if (state->lines[i] != LINE_UNKNOWN)
2764 continue;
2765
2766 eqclass = dsf_canonify(sstate->dotdsf, d1);
2767 if (eqclass != dsf_canonify(sstate->dotdsf, d2))
2768 continue;
2769
2770 val = LINE_NO; /* loop is bad until proven otherwise */
2771
2772 /*
2773 * This edge would form a loop. Next
2774 * question: how long would the loop be?
2775 * Would it equal the total number of edges
2776 * (plus the one we'd be adding if we added
2777 * it)?
2778 */
2779 if (sstate->looplen[eqclass] == edgecount + 1) {
2780 int sm1_nearby;
2781
2782 /*
2783 * This edge would form a loop which
2784 * took in all the edges in the entire
2785 * grid. So now we need to work out
2786 * whether it would be a valid solution
2787 * to the puzzle, which means we have to
2788 * check if it satisfies all the clues.
2789 * This means that every clue must be
2790 * either satisfied or satisfied-minus-
2791 * 1, and also that the number of
2792 * satisfied-minus-1 clues must be at
2793 * most two and they must lie on either
2794 * side of this edge.
2795 */
2796 sm1_nearby = 0;
2797 if (e->face1) {
2798 int f = e->face1 - g->faces;
2799 int c = state->clues[f];
2800 if (c >= 0 && sstate->face_yes_count[f] == c - 1)
2801 sm1_nearby++;
2802 }
2803 if (e->face2) {
2804 int f = e->face2 - g->faces;
2805 int c = state->clues[f];
2806 if (c >= 0 && sstate->face_yes_count[f] == c - 1)
2807 sm1_nearby++;
2808 }
2809 if (sm1clues == sm1_nearby &&
2810 sm1clues + satclues == clues) {
2811 val = LINE_YES; /* loop is good! */
2812 }
2813 }
2814
2815 /*
2816 * Right. Now we know that adding this edge
2817 * would form a loop, and we know whether
2818 * that loop would be a viable solution or
2819 * not.
2820 *
2821 * If adding this edge produces a solution,
2822 * then we know we've found _a_ solution but
2823 * we don't know that it's _the_ solution -
2824 * if it were provably the solution then
2825 * we'd have deduced this edge some time ago
2826 * without the need to do loop detection. So
2827 * in this state we return SOLVER_AMBIGUOUS,
2828 * which has the effect that hitting Solve
2829 * on a user-provided puzzle will fill in a
2830 * solution but using the solver to
2831 * construct new puzzles won't consider this
2832 * a reasonable deduction for the user to
2833 * make.
2834 */
2835 progress = solver_set_line(sstate, i, val);
2836 assert(progress == TRUE);
2837 if (val == LINE_YES) {
2838 sstate->solver_status = SOLVER_AMBIGUOUS;
2839 goto finished_loop_deductionsing;
2840 }
2841 }
2842
2843 finished_loop_deductionsing:
2844 return progress ? DIFF_EASY : DIFF_MAX;
2845}
2846
2847/* This will return a dynamically allocated solver_state containing the (more)
2848 * solved grid */
2849static solver_state *solve_game_rec(const solver_state *sstate_start)
2850{
2851 solver_state *sstate;
2852
2853 /* Index of the solver we should call next. */
2854 int i = 0;
2855
2856 /* As a speed-optimisation, we avoid re-running solvers that we know
2857 * won't make any progress. This happens when a high-difficulty
2858 * solver makes a deduction that can only help other high-difficulty
2859 * solvers.
2860 * For example: if a new 'dline' flag is set by dline_deductions, the
2861 * trivial_deductions solver cannot do anything with this information.
2862 * If we've already run the trivial_deductions solver (because it's
2863 * earlier in the list), there's no point running it again.
2864 *
2865 * Therefore: if a solver is earlier in the list than "threshold_index",
2866 * we don't bother running it if it's difficulty level is less than
2867 * "threshold_diff".
2868 */
2869 int threshold_diff = 0;
2870 int threshold_index = 0;
2871
2872 sstate = dup_solver_state(sstate_start);
2873
2874 check_caches(sstate);
2875
2876 while (i < NUM_SOLVERS) {
2877 if (sstate->solver_status == SOLVER_MISTAKE)
2878 return sstate;
2879 if (sstate->solver_status == SOLVER_SOLVED ||
2880 sstate->solver_status == SOLVER_AMBIGUOUS) {
2881 /* solver finished */
2882 break;
2883 }
2884
2885 if ((solver_diffs[i] >= threshold_diff || i >= threshold_index)
2886 && solver_diffs[i] <= sstate->diff) {
2887 /* current_solver is eligible, so use it */
2888 int next_diff = solver_fns[i](sstate);
2889 if (next_diff != DIFF_MAX) {
2890 /* solver made progress, so use new thresholds and
2891 * start again at top of list. */
2892 threshold_diff = next_diff;
2893 threshold_index = i;
2894 i = 0;
2895 continue;
2896 }
2897 }
2898 /* current_solver is ineligible, or failed to make progress, so
2899 * go to the next solver in the list */
2900 i++;
2901 }
2902
2903 if (sstate->solver_status == SOLVER_SOLVED ||
2904 sstate->solver_status == SOLVER_AMBIGUOUS) {
2905 /* s/LINE_UNKNOWN/LINE_NO/g */
2906 array_setall(sstate->state->lines, LINE_UNKNOWN, LINE_NO,
2907 sstate->state->game_grid->num_edges);
2908 return sstate;
2909 }
2910
2911 return sstate;
2912}
2913
2914static char *solve_game(const game_state *state, const game_state *currstate,
2915 const char *aux, char **error)
2916{
2917 char *soln = NULL;
2918 solver_state *sstate, *new_sstate;
2919
2920 sstate = new_solver_state(state, DIFF_MAX);
2921 new_sstate = solve_game_rec(sstate);
2922
2923 if (new_sstate->solver_status == SOLVER_SOLVED) {
2924 soln = encode_solve_move(new_sstate->state);
2925 } else if (new_sstate->solver_status == SOLVER_AMBIGUOUS) {
2926 soln = encode_solve_move(new_sstate->state);
2927 /**error = "Solver found ambiguous solutions"; */
2928 } else {
2929 soln = encode_solve_move(new_sstate->state);
2930 /**error = "Solver failed"; */
2931 }
2932
2933 free_solver_state(new_sstate);
2934 free_solver_state(sstate);
2935
2936 return soln;
2937}
2938
2939/* ----------------------------------------------------------------------
2940 * Drawing and mouse-handling
2941 */
2942
2943static char *interpret_move(const game_state *state, game_ui *ui,
2944 const game_drawstate *ds,
2945 int x, int y, int button)
2946{
2947 grid *g = state->game_grid;
2948 grid_edge *e;
2949 int i;
2950 char *movebuf;
2951 int movelen, movesize;
2952 char button_char = ' ';
2953 enum line_state old_state;
2954
2955 button &= ~MOD_MASK;
2956
2957 /* Convert mouse-click (x,y) to grid coordinates */
2958 x -= BORDER(ds->tilesize);
2959 y -= BORDER(ds->tilesize);
2960 x = x * g->tilesize / ds->tilesize;
2961 y = y * g->tilesize / ds->tilesize;
2962 x += g->lowest_x;
2963 y += g->lowest_y;
2964
2965 e = grid_nearest_edge(g, x, y);
2966 if (e == NULL)
2967 return NULL;
2968
2969 i = e - g->edges;
2970
2971 /* I think it's only possible to play this game with mouse clicks, sorry */
2972 /* Maybe will add mouse drag support some time */
2973 old_state = state->lines[i];
2974
2975 switch (button) {
2976 case LEFT_BUTTON:
2977 switch (old_state) {
2978 case LINE_UNKNOWN:
2979 button_char = 'y';
2980 break;
2981 case LINE_YES:
2982#ifdef STYLUS_BASED
2983 button_char = 'n';
2984 break;
2985#endif
2986 case LINE_NO:
2987 button_char = 'u';
2988 break;
2989 }
2990 break;
2991 case MIDDLE_BUTTON:
2992 button_char = 'u';
2993 break;
2994 case RIGHT_BUTTON:
2995 switch (old_state) {
2996 case LINE_UNKNOWN:
2997 button_char = 'n';
2998 break;
2999 case LINE_NO:
3000#ifdef STYLUS_BASED
3001 button_char = 'y';
3002 break;
3003#endif
3004 case LINE_YES:
3005 button_char = 'u';
3006 break;
3007 }
3008 break;
3009 default:
3010 return NULL;
3011 }
3012
3013 movelen = 0;
3014 movesize = 80;
3015 movebuf = snewn(movesize, char);
3016 movelen = sprintf(movebuf, "%d%c", i, (int)button_char);
3017 {
3018 static enum { OFF, FIXED, ADAPTIVE, DUNNO } autofollow = DUNNO;
3019 if (autofollow == DUNNO) {
3020 const char *env = getenv("LOOPY_AUTOFOLLOW");
3021 if (env && !strcmp(env, "off"))
3022 autofollow = OFF;
3023 else if (env && !strcmp(env, "fixed"))
3024 autofollow = FIXED;
3025 else if (env && !strcmp(env, "adaptive"))
3026 autofollow = ADAPTIVE;
3027 else
3028 autofollow = OFF;
3029 }
3030
3031 if (autofollow != OFF) {
3032 int dotid;
3033 for (dotid = 0; dotid < 2; dotid++) {
3034 grid_dot *dot = (dotid == 0 ? e->dot1 : e->dot2);
3035 grid_edge *e_this = e;
3036
3037 while (1) {
3038 int j, n_found;
3039 grid_edge *e_next = NULL;
3040
3041 for (j = n_found = 0; j < dot->order; j++) {
3042 grid_edge *e_candidate = dot->edges[j];
3043 int i_candidate = e_candidate - g->edges;
3044 if (e_candidate != e_this &&
3045 (autofollow == FIXED ||
3046 state->lines[i] == LINE_NO ||
3047 state->lines[i_candidate] != LINE_NO)) {
3048 e_next = e_candidate;
3049 n_found++;
3050 }
3051 }
3052
3053 if (n_found != 1 ||
3054 state->lines[e_next - g->edges] != state->lines[i])
3055 break;
3056
3057 dot = (e_next->dot1 != dot ? e_next->dot1 : e_next->dot2);
3058 if (movelen > movesize - 40) {
3059 movesize = movesize * 5 / 4 + 128;
3060 movebuf = sresize(movebuf, movesize, char);
3061 }
3062 e_this = e_next;
3063 movelen += sprintf(movebuf+movelen, "%d%c",
3064 (int)(e_this - g->edges), button_char);
3065 }
3066 }
3067 }
3068 }
3069
3070 return sresize(movebuf, movelen+1, char);
3071}
3072
3073static game_state *execute_move(const game_state *state, const char *move)
3074{
3075 int i;
3076 game_state *newstate = dup_game(state);
3077
3078 if (move[0] == 'S') {
3079 move++;
3080 newstate->cheated = TRUE;
3081 }
3082
3083 while (*move) {
3084 i = atoi(move);
3085 if (i < 0 || i >= newstate->game_grid->num_edges)
3086 goto fail;
3087 move += strspn(move, "1234567890");
3088 switch (*(move++)) {
3089 case 'y':
3090 newstate->lines[i] = LINE_YES;
3091 break;
3092 case 'n':
3093 newstate->lines[i] = LINE_NO;
3094 break;
3095 case 'u':
3096 newstate->lines[i] = LINE_UNKNOWN;
3097 break;
3098 default:
3099 goto fail;
3100 }
3101 }
3102
3103 /*
3104 * Check for completion.
3105 */
3106 if (check_completion(newstate))
3107 newstate->solved = TRUE;
3108
3109 return newstate;
3110
3111 fail:
3112 free_game(newstate);
3113 return NULL;
3114}
3115
3116/* ----------------------------------------------------------------------
3117 * Drawing routines.
3118 */
3119
3120/* Convert from grid coordinates to screen coordinates */
3121static void grid_to_screen(const game_drawstate *ds, const grid *g,
3122 int grid_x, int grid_y, int *x, int *y)
3123{
3124 *x = grid_x - g->lowest_x;
3125 *y = grid_y - g->lowest_y;
3126 *x = *x * ds->tilesize / g->tilesize;
3127 *y = *y * ds->tilesize / g->tilesize;
3128 *x += BORDER(ds->tilesize);
3129 *y += BORDER(ds->tilesize);
3130}
3131
3132/* Returns (into x,y) position of centre of face for rendering the text clue.
3133 */
3134static void face_text_pos(const game_drawstate *ds, const grid *g,
3135 grid_face *f, int *xret, int *yret)
3136{
3137 int faceindex = f - g->faces;
3138
3139 /*
3140 * Return the cached position for this face, if we've already
3141 * worked it out.
3142 */
3143 if (ds->textx[faceindex] >= 0) {
3144 *xret = ds->textx[faceindex];
3145 *yret = ds->texty[faceindex];
3146 return;
3147 }
3148
3149 /*
3150 * Otherwise, use the incentre computed by grid.c and convert it
3151 * to screen coordinates.
3152 */
3153 grid_find_incentre(f);
3154 grid_to_screen(ds, g, f->ix, f->iy,
3155 &ds->textx[faceindex], &ds->texty[faceindex]);
3156
3157 *xret = ds->textx[faceindex];
3158 *yret = ds->texty[faceindex];
3159}
3160
3161static void face_text_bbox(game_drawstate *ds, grid *g, grid_face *f,
3162 int *x, int *y, int *w, int *h)
3163{
3164 int xx, yy;
3165 face_text_pos(ds, g, f, &xx, &yy);
3166
3167 /* There seems to be a certain amount of trial-and-error involved
3168 * in working out the correct bounding-box for the text. */
3169
3170 *x = xx - ds->tilesize/4 - 1;
3171 *y = yy - ds->tilesize/4 - 3;
3172 *w = ds->tilesize/2 + 2;
3173 *h = ds->tilesize/2 + 5;
3174}
3175
3176static void game_redraw_clue(drawing *dr, game_drawstate *ds,
3177 const game_state *state, int i)
3178{
3179 grid *g = state->game_grid;
3180 grid_face *f = g->faces + i;
3181 int x, y;
3182 char c[20];
3183
3184 sprintf(c, "%d", state->clues[i]);
3185
3186 face_text_pos(ds, g, f, &x, &y);
3187 draw_text(dr, x, y,
3188 FONT_VARIABLE, ds->tilesize/2,
3189 ALIGN_VCENTRE | ALIGN_HCENTRE,
3190 ds->clue_error[i] ? COL_MISTAKE :
3191 ds->clue_satisfied[i] ? COL_SATISFIED : COL_FOREGROUND, c);
3192}
3193
3194static void edge_bbox(game_drawstate *ds, grid *g, grid_edge *e,
3195 int *x, int *y, int *w, int *h)
3196{
3197 int x1 = e->dot1->x;
3198 int y1 = e->dot1->y;
3199 int x2 = e->dot2->x;
3200 int y2 = e->dot2->y;
3201 int xmin, xmax, ymin, ymax;
3202
3203 grid_to_screen(ds, g, x1, y1, &x1, &y1);
3204 grid_to_screen(ds, g, x2, y2, &x2, &y2);
3205 /* Allow extra margin for dots, and thickness of lines */
3206 xmin = min(x1, x2) - 2;
3207 xmax = max(x1, x2) + 2;
3208 ymin = min(y1, y2) - 2;
3209 ymax = max(y1, y2) + 2;
3210
3211 *x = xmin;
3212 *y = ymin;
3213 *w = xmax - xmin + 1;
3214 *h = ymax - ymin + 1;
3215}
3216
3217static void dot_bbox(game_drawstate *ds, grid *g, grid_dot *d,
3218 int *x, int *y, int *w, int *h)
3219{
3220 int x1, y1;
3221
3222 grid_to_screen(ds, g, d->x, d->y, &x1, &y1);
3223
3224 *x = x1 - 2;
3225 *y = y1 - 2;
3226 *w = 5;
3227 *h = 5;
3228}
3229
3230static const int loopy_line_redraw_phases[] = {
3231 COL_FAINT, COL_LINEUNKNOWN, COL_FOREGROUND, COL_HIGHLIGHT, COL_MISTAKE
3232};
3233#define NPHASES lenof(loopy_line_redraw_phases)
3234
3235static void game_redraw_line(drawing *dr, game_drawstate *ds,
3236 const game_state *state, int i, int phase)
3237{
3238 grid *g = state->game_grid;
3239 grid_edge *e = g->edges + i;
3240 int x1, x2, y1, y2;
3241 int line_colour;
3242
3243 if (state->line_errors[i])
3244 line_colour = COL_MISTAKE;
3245 else if (state->lines[i] == LINE_UNKNOWN)
3246 line_colour = COL_LINEUNKNOWN;
3247 else if (state->lines[i] == LINE_NO)
3248 line_colour = COL_FAINT;
3249 else if (ds->flashing)
3250 line_colour = COL_HIGHLIGHT;
3251 else
3252 line_colour = COL_FOREGROUND;
3253 if (line_colour != loopy_line_redraw_phases[phase])
3254 return;
3255
3256 /* Convert from grid to screen coordinates */
3257 grid_to_screen(ds, g, e->dot1->x, e->dot1->y, &x1, &y1);
3258 grid_to_screen(ds, g, e->dot2->x, e->dot2->y, &x2, &y2);
3259
3260 if (line_colour == COL_FAINT) {
3261 static int draw_faint_lines = -1;
3262 if (draw_faint_lines < 0) {
3263 char *env = getenv("LOOPY_FAINT_LINES");
3264 draw_faint_lines = (!env || (env[0] == 'y' ||
3265 env[0] == 'Y'));
3266 }
3267 if (draw_faint_lines)
3268 draw_line(dr, x1, y1, x2, y2, line_colour);
3269 } else {
3270 draw_thick_line(dr, 3.0,
3271 x1 + 0.5, y1 + 0.5,
3272 x2 + 0.5, y2 + 0.5,
3273 line_colour);
3274 }
3275}
3276
3277static void game_redraw_dot(drawing *dr, game_drawstate *ds,
3278 const game_state *state, int i)
3279{
3280 grid *g = state->game_grid;
3281 grid_dot *d = g->dots + i;
3282 int x, y;
3283
3284 grid_to_screen(ds, g, d->x, d->y, &x, &y);
3285 draw_circle(dr, x, y, 2, COL_FOREGROUND, COL_FOREGROUND);
3286}
3287
3288static int boxes_intersect(int x0, int y0, int w0, int h0,
3289 int x1, int y1, int w1, int h1)
3290{
3291 /*
3292 * Two intervals intersect iff neither is wholly on one side of
3293 * the other. Two boxes intersect iff their horizontal and
3294 * vertical intervals both intersect.
3295 */
3296 return (x0 < x1+w1 && x1 < x0+w0 && y0 < y1+h1 && y1 < y0+h0);
3297}
3298
3299static void game_redraw_in_rect(drawing *dr, game_drawstate *ds,
3300 const game_state *state,
3301 int x, int y, int w, int h)
3302{
3303 grid *g = state->game_grid;
3304 int i, phase;
3305 int bx, by, bw, bh;
3306
3307 clip(dr, x, y, w, h);
3308 draw_rect(dr, x, y, w, h, COL_BACKGROUND);
3309
3310 for (i = 0; i < g->num_faces; i++) {
3311 if (state->clues[i] >= 0) {
3312 face_text_bbox(ds, g, &g->faces[i], &bx, &by, &bw, &bh);
3313 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3314 game_redraw_clue(dr, ds, state, i);
3315 }
3316 }
3317 for (phase = 0; phase < NPHASES; phase++) {
3318 for (i = 0; i < g->num_edges; i++) {
3319 edge_bbox(ds, g, &g->edges[i], &bx, &by, &bw, &bh);
3320 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3321 game_redraw_line(dr, ds, state, i, phase);
3322 }
3323 }
3324 for (i = 0; i < g->num_dots; i++) {
3325 dot_bbox(ds, g, &g->dots[i], &bx, &by, &bw, &bh);
3326 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3327 game_redraw_dot(dr, ds, state, i);
3328 }
3329
3330 unclip(dr);
3331 draw_update(dr, x, y, w, h);
3332}
3333
3334static void game_redraw(drawing *dr, game_drawstate *ds,
3335 const game_state *oldstate, const game_state *state,
3336 int dir, const game_ui *ui,
3337 float animtime, float flashtime)
3338{
3339#define REDRAW_OBJECTS_LIMIT 16 /* Somewhat arbitrary tradeoff */
3340
3341 grid *g = state->game_grid;
3342 int border = BORDER(ds->tilesize);
3343 int i;
3344 int flash_changed;
3345 int redraw_everything = FALSE;
3346
3347 int edges[REDRAW_OBJECTS_LIMIT], nedges = 0;
3348 int faces[REDRAW_OBJECTS_LIMIT], nfaces = 0;
3349
3350 /* Redrawing is somewhat involved.
3351 *
3352 * An update can theoretically affect an arbitrary number of edges
3353 * (consider, for example, completing or breaking a cycle which doesn't
3354 * satisfy all the clues -- we'll switch many edges between error and
3355 * normal states). On the other hand, redrawing the whole grid takes a
3356 * while, making the game feel sluggish, and many updates are actually
3357 * quite well localized.
3358 *
3359 * This redraw algorithm attempts to cope with both situations gracefully
3360 * and correctly. For localized changes, we set a clip rectangle, fill
3361 * it with background, and then redraw (a plausible but conservative
3362 * guess at) the objects which intersect the rectangle; if several
3363 * objects need redrawing, we'll do them individually. However, if lots
3364 * of objects are affected, we'll just redraw everything.
3365 *
3366 * The reason for all of this is that it's just not safe to do the redraw
3367 * piecemeal. If you try to draw an antialiased diagonal line over
3368 * itself, you get a slightly thicker antialiased diagonal line, which
3369 * looks rather ugly after a while.
3370 *
3371 * So, we take two passes over the grid. The first attempts to work out
3372 * what needs doing, and the second actually does it.
3373 */
3374
3375 if (!ds->started) {
3376 redraw_everything = TRUE;
3377 /*
3378 * But we must still go through the upcoming loops, so that we
3379 * set up stuff in ds correctly for the initial redraw.
3380 */
3381 }
3382
3383 /* First, trundle through the faces. */
3384 for (i = 0; i < g->num_faces; i++) {
3385 grid_face *f = g->faces + i;
3386 int sides = f->order;
3387 int yes_order, no_order;
3388 int clue_mistake;
3389 int clue_satisfied;
3390 int n = state->clues[i];
3391 if (n < 0)
3392 continue;
3393
3394 yes_order = face_order(state, i, LINE_YES);
3395 if (state->exactly_one_loop) {
3396 /*
3397 * Special case: if the set of LINE_YES edges in the grid
3398 * consists of exactly one loop and nothing else, then we
3399 * switch to treating LINE_UNKNOWN the same as LINE_NO for
3400 * purposes of clue checking.
3401 *
3402 * This is because some people like to play Loopy without
3403 * using the right-click, i.e. never setting anything to
3404 * LINE_NO. Without this special case, if a person playing
3405 * in that style fills in what they think is a correct
3406 * solution loop but in fact it has an underfilled clue,
3407 * then we will display no victory flash and also no error
3408 * highlight explaining why not. With this special case,
3409 * we light up underfilled clues at the instant the loop
3410 * is closed. (Of course, *overfilled* clues are fine
3411 * either way.)
3412 *
3413 * (It might still be considered unfortunate that we can't
3414 * warn this style of player any earlier, if they make a
3415 * mistake very near the beginning which doesn't show up
3416 * until they close the last edge of the loop. One other
3417 * thing we _could_ do here is to treat any LINE_UNKNOWN
3418 * as LINE_NO if either of its endpoints has yes-degree 2,
3419 * reflecting the fact that setting that line to YES would
3420 * be an obvious error. But I don't think even that could
3421 * catch _all_ clue errors in a timely manner; I think
3422 * there are some that won't be displayed until the loop
3423 * is filled in, even so, and there's no way to avoid that
3424 * with complete reliability except to switch to being a
3425 * player who sets things to LINE_NO.)
3426 */
3427 no_order = sides - yes_order;
3428 } else {
3429 no_order = face_order(state, i, LINE_NO);
3430 }
3431
3432 clue_mistake = (yes_order > n || no_order > (sides-n));
3433 clue_satisfied = (yes_order == n && no_order == (sides-n));
3434
3435 if (clue_mistake != ds->clue_error[i] ||
3436 clue_satisfied != ds->clue_satisfied[i]) {
3437 ds->clue_error[i] = clue_mistake;
3438 ds->clue_satisfied[i] = clue_satisfied;
3439 if (nfaces == REDRAW_OBJECTS_LIMIT)
3440 redraw_everything = TRUE;
3441 else
3442 faces[nfaces++] = i;
3443 }
3444 }
3445
3446 /* Work out what the flash state needs to be. */
3447 if (flashtime > 0 &&
3448 (flashtime <= FLASH_TIME/3 ||
3449 flashtime >= FLASH_TIME*2/3)) {
3450 flash_changed = !ds->flashing;
3451 ds->flashing = TRUE;
3452 } else {
3453 flash_changed = ds->flashing;
3454 ds->flashing = FALSE;
3455 }
3456
3457 /* Now, trundle through the edges. */
3458 for (i = 0; i < g->num_edges; i++) {
3459 char new_ds =
3460 state->line_errors[i] ? DS_LINE_ERROR : state->lines[i];
3461 if (new_ds != ds->lines[i] ||
3462 (flash_changed && state->lines[i] == LINE_YES)) {
3463 ds->lines[i] = new_ds;
3464 if (nedges == REDRAW_OBJECTS_LIMIT)
3465 redraw_everything = TRUE;
3466 else
3467 edges[nedges++] = i;
3468 }
3469 }
3470
3471 /* Pass one is now done. Now we do the actual drawing. */
3472 if (redraw_everything) {
3473 int grid_width = g->highest_x - g->lowest_x;
3474 int grid_height = g->highest_y - g->lowest_y;
3475 int w = grid_width * ds->tilesize / g->tilesize;
3476 int h = grid_height * ds->tilesize / g->tilesize;
3477
3478 game_redraw_in_rect(dr, ds, state,
3479 0, 0, w + 2*border + 1, h + 2*border + 1);
3480 } else {
3481
3482 /* Right. Now we roll up our sleeves. */
3483
3484 for (i = 0; i < nfaces; i++) {
3485 grid_face *f = g->faces + faces[i];
3486 int x, y, w, h;
3487
3488 face_text_bbox(ds, g, f, &x, &y, &w, &h);
3489 game_redraw_in_rect(dr, ds, state, x, y, w, h);
3490 }
3491
3492 for (i = 0; i < nedges; i++) {
3493 grid_edge *e = g->edges + edges[i];
3494 int x, y, w, h;
3495
3496 edge_bbox(ds, g, e, &x, &y, &w, &h);
3497 game_redraw_in_rect(dr, ds, state, x, y, w, h);
3498 }
3499 }
3500
3501 ds->started = TRUE;
3502}
3503
3504static float game_flash_length(const game_state *oldstate,
3505 const game_state *newstate, int dir, game_ui *ui)
3506{
3507 if (!oldstate->solved && newstate->solved &&
3508 !oldstate->cheated && !newstate->cheated) {
3509 return FLASH_TIME;
3510 }
3511
3512 return 0.0F;
3513}
3514
3515static int game_status(const game_state *state)
3516{
3517 return state->solved ? +1 : 0;
3518}
3519
3520static void game_print_size(const game_params *params, float *x, float *y)
3521{
3522 int pw, ph;
3523
3524 /*
3525 * I'll use 7mm "squares" by default.
3526 */
3527 game_compute_size(params, 700, &pw, &ph);
3528 *x = pw / 100.0F;
3529 *y = ph / 100.0F;
3530}
3531
3532static void game_print(drawing *dr, const game_state *state, int tilesize)
3533{
3534 int ink = print_mono_colour(dr, 0);
3535 int i;
3536 game_drawstate ads, *ds = &ads;
3537 grid *g = state->game_grid;
3538
3539 ds->tilesize = tilesize;
3540 ds->textx = snewn(g->num_faces, int);
3541 ds->texty = snewn(g->num_faces, int);
3542 for (i = 0; i < g->num_faces; i++)
3543 ds->textx[i] = ds->texty[i] = -1;
3544
3545 for (i = 0; i < g->num_dots; i++) {
3546 int x, y;
3547 grid_to_screen(ds, g, g->dots[i].x, g->dots[i].y, &x, &y);
3548 draw_circle(dr, x, y, ds->tilesize / 15, ink, ink);
3549 }
3550
3551 /*
3552 * Clues.
3553 */
3554 for (i = 0; i < g->num_faces; i++) {
3555 grid_face *f = g->faces + i;
3556 int clue = state->clues[i];
3557 if (clue >= 0) {
3558 char c[20];
3559 int x, y;
3560 sprintf(c, "%d", state->clues[i]);
3561 face_text_pos(ds, g, f, &x, &y);
3562 draw_text(dr, x, y,
3563 FONT_VARIABLE, ds->tilesize / 2,
3564 ALIGN_VCENTRE | ALIGN_HCENTRE, ink, c);
3565 }
3566 }
3567
3568 /*
3569 * Lines.
3570 */
3571 for (i = 0; i < g->num_edges; i++) {
3572 int thickness = (state->lines[i] == LINE_YES) ? 30 : 150;
3573 grid_edge *e = g->edges + i;
3574 int x1, y1, x2, y2;
3575 grid_to_screen(ds, g, e->dot1->x, e->dot1->y, &x1, &y1);
3576 grid_to_screen(ds, g, e->dot2->x, e->dot2->y, &x2, &y2);
3577 if (state->lines[i] == LINE_YES)
3578 {
3579 /* (dx, dy) points from (x1, y1) to (x2, y2).
3580 * The line is then "fattened" in a perpendicular
3581 * direction to create a thin rectangle. */
3582 double d = sqrt(SQ((double)x1 - x2) + SQ((double)y1 - y2));
3583 double dx = (x2 - x1) / d;
3584 double dy = (y2 - y1) / d;
3585 int points[8];
3586
3587 dx = (dx * ds->tilesize) / thickness;
3588 dy = (dy * ds->tilesize) / thickness;
3589 points[0] = x1 + (int)dy;
3590 points[1] = y1 - (int)dx;
3591 points[2] = x1 - (int)dy;
3592 points[3] = y1 + (int)dx;
3593 points[4] = x2 - (int)dy;
3594 points[5] = y2 + (int)dx;
3595 points[6] = x2 + (int)dy;
3596 points[7] = y2 - (int)dx;
3597 draw_polygon(dr, points, 4, ink, ink);
3598 }
3599 else
3600 {
3601 /* Draw a dotted line */
3602 int divisions = 6;
3603 int j;
3604 for (j = 1; j < divisions; j++) {
3605 /* Weighted average */
3606 int x = (x1 * (divisions -j) + x2 * j) / divisions;
3607 int y = (y1 * (divisions -j) + y2 * j) / divisions;
3608 draw_circle(dr, x, y, ds->tilesize / thickness, ink, ink);
3609 }
3610 }
3611 }
3612
3613 sfree(ds->textx);
3614 sfree(ds->texty);
3615}
3616
3617#ifdef COMBINED
3618#define thegame loopy
3619#endif
3620
3621const struct game thegame = {
3622 "Loopy", "games.loopy", "loopy",
3623 default_params,
3624 NULL, game_preset_menu,
3625 decode_params,
3626 encode_params,
3627 free_params,
3628 dup_params,
3629 TRUE, game_configure, custom_params,
3630 validate_params,
3631 new_game_desc,
3632 validate_desc,
3633 new_game,
3634 dup_game,
3635 free_game,
3636 1, solve_game,
3637 TRUE, game_can_format_as_text_now, game_text_format,
3638 new_ui,
3639 free_ui,
3640 encode_ui,
3641 decode_ui,
3642 game_changed_state,
3643 interpret_move,
3644 execute_move,
3645 PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
3646 game_colours,
3647 game_new_drawstate,
3648 game_free_drawstate,
3649 game_redraw,
3650 game_anim_length,
3651 game_flash_length,
3652 game_status,
3653 TRUE, FALSE, game_print_size, game_print,
3654 FALSE /* wants_statusbar */,
3655 FALSE, game_timing_state,
3656 0, /* mouse_priorities */
3657};
3658
3659#ifdef STANDALONE_SOLVER
3660
3661/*
3662 * Half-hearted standalone solver. It can't output the solution to
3663 * anything but a square puzzle, and it can't log the deductions
3664 * it makes either. But it can solve square puzzles, and more
3665 * importantly it can use its solver to grade the difficulty of
3666 * any puzzle you give it.
3667 */
3668
3669#include <stdarg.h>
3670
3671int main(int argc, char **argv)
3672{
3673 game_params *p;
3674 game_state *s;
3675 char *id = NULL, *desc, *err;
3676 int grade = FALSE;
3677 int ret, diff;
3678#if 0 /* verbose solver not supported here (yet) */
3679 int really_verbose = FALSE;
3680#endif
3681
3682 while (--argc > 0) {
3683 char *p = *++argv;
3684#if 0 /* verbose solver not supported here (yet) */
3685 if (!strcmp(p, "-v")) {
3686 really_verbose = TRUE;
3687 } else
3688#endif
3689 if (!strcmp(p, "-g")) {
3690 grade = TRUE;
3691 } else if (*p == '-') {
3692 fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0], p);
3693 return 1;
3694 } else {
3695 id = p;
3696 }
3697 }
3698
3699 if (!id) {
3700 fprintf(stderr, "usage: %s [-g | -v] <game_id>\n", argv[0]);
3701 return 1;
3702 }
3703
3704 desc = strchr(id, ':');
3705 if (!desc) {
3706 fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]);
3707 return 1;
3708 }
3709 *desc++ = '\0';
3710
3711 p = default_params();
3712 decode_params(p, id);
3713 err = validate_desc(p, desc);
3714 if (err) {
3715 fprintf(stderr, "%s: %s\n", argv[0], err);
3716 return 1;
3717 }
3718 s = new_game(NULL, p, desc);
3719
3720 /*
3721 * When solving an Easy puzzle, we don't want to bother the
3722 * user with Hard-level deductions. For this reason, we grade
3723 * the puzzle internally before doing anything else.
3724 */
3725 ret = -1; /* placate optimiser */
3726 for (diff = 0; diff < DIFF_MAX; diff++) {
3727 solver_state *sstate_new;
3728 solver_state *sstate = new_solver_state((game_state *)s, diff);
3729
3730 sstate_new = solve_game_rec(sstate);
3731
3732 if (sstate_new->solver_status == SOLVER_MISTAKE)
3733 ret = 0;
3734 else if (sstate_new->solver_status == SOLVER_SOLVED)
3735 ret = 1;
3736 else
3737 ret = 2;
3738
3739 free_solver_state(sstate_new);
3740 free_solver_state(sstate);
3741
3742 if (ret < 2)
3743 break;
3744 }
3745
3746 if (diff == DIFF_MAX) {
3747 if (grade)
3748 printf("Difficulty rating: harder than Hard, or ambiguous\n");
3749 else
3750 printf("Unable to find a unique solution\n");
3751 } else {
3752 if (grade) {
3753 if (ret == 0)
3754 printf("Difficulty rating: impossible (no solution exists)\n");
3755 else if (ret == 1)
3756 printf("Difficulty rating: %s\n", diffnames[diff]);
3757 } else {
3758 solver_state *sstate_new;
3759 solver_state *sstate = new_solver_state((game_state *)s, diff);
3760
3761 /* If we supported a verbose solver, we'd set verbosity here */
3762
3763 sstate_new = solve_game_rec(sstate);
3764
3765 if (sstate_new->solver_status == SOLVER_MISTAKE)
3766 printf("Puzzle is inconsistent\n");
3767 else {
3768 assert(sstate_new->solver_status == SOLVER_SOLVED);
3769 if (s->grid_type == 0) {
3770 fputs(game_text_format(sstate_new->state), stdout);
3771 } else {
3772 printf("Unable to output non-square grids\n");
3773 }
3774 }
3775
3776 free_solver_state(sstate_new);
3777 free_solver_state(sstate);
3778 }
3779 }
3780
3781 return 0;
3782}
3783
3784#endif
3785
3786/* vim: set shiftwidth=4 tabstop=8: */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 15:05:28 +0000