1 /*
2 * slant.c: Puzzle from nikoli.co.jp involving drawing a diagonal
3 * line through each square of a grid.
4 */
5
6 /*
7 * In this puzzle you have a grid of squares, each of which must
8 * contain a diagonal line; you also have clue numbers placed at
9 * _points_ of that grid, which means there's a (w+1) x (h+1) array
10 * of possible clue positions.
11 *
12 * I'm therefore going to adopt a rigid convention throughout this
13 * source file of using w and h for the dimensions of the grid of
14 * squares, and W and H for the dimensions of the grid of points.
15 * Thus, W == w+1 and H == h+1 always.
16 *
17 * Clue arrays will be W*H `signed char's, and the clue at each
18 * point will be a number from 0 to 4, or -1 if there's no clue.
19 *
20 * Solution arrays will be W*H `signed char's, and the number at
21 * each point will be +1 for a forward slash (/), -1 for a
22 * backslash (\), and 0 for unknown.
23 */
24
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <stdarg.h>
28 #include <string.h>
29 #include <assert.h>
30 #include <ctype.h>
31 #include <math.h>
32
33 #include "puzzles.h"
34
35 enum {
36 COL_BACKGROUND,
37 COL_GRID,
38 COL_INK,
39 COL_SLANT1,
40 COL_SLANT2,
41 COL_ERROR,
42 COL_CURSOR,
43 COL_FILLEDSQUARE,
44 NCOLOURS
45 };
46
47 /*
48 * In standalone solver mode, `verbose' is a variable which can be
49 * set by command-line option; in debugging mode it's simply always
50 * true.
51 */
52 #if defined STANDALONE_SOLVER
53 #define SOLVER_DIAGNOSTICS
54 bool verbose = false;
55 #elif defined SOLVER_DIAGNOSTICS
56 #define verbose true
57 #endif
58
59 /*
60 * Difficulty levels. I do some macro ickery here to ensure that my
61 * enum and the various forms of my name list always match up.
62 */
63 #define DIFFLIST(A) \
64 A(EASY,Easy,e) \
65 A(HARD,Hard,h)
66 #define ENUM(upper,title,lower) DIFF_ ## upper,
67 #define TITLE(upper,title,lower) #title,
68 #define ENCODE(upper,title,lower) #lower
69 #define CONFIG(upper,title,lower) ":" #title
70 enum { DIFFLIST(ENUM) DIFFCOUNT };
71 static char const *const slant_diffnames[] = { DIFFLIST(TITLE) };
72 static char const slant_diffchars[] = DIFFLIST(ENCODE);
73 #define DIFFCONFIG DIFFLIST(CONFIG)
74
75 struct game_params {
76 int w, h, diff;
77 };
78
79 typedef struct game_clues {
80 int w, h;
81 signed char *clues;
82 int *tmpdsf;
83 int refcount;
84 } game_clues;
85
86 #define ERR_VERTEX 1
87 #define ERR_SQUARE 2
88
89 struct game_state {
90 struct game_params p;
91 game_clues *clues;
92 signed char *soln;
93 unsigned char *errors;
94 bool completed;
95 bool used_solve; /* used to suppress completion flash */
96 };
97
default_params(void)98 static game_params *default_params(void)
99 {
100 game_params *ret = snew(game_params);
101
102 ret->w = ret->h = 8;
103 ret->diff = DIFF_EASY;
104
105 return ret;
106 }
107
108 static const struct game_params slant_presets[] = {
109 {5, 5, DIFF_EASY},
110 {5, 5, DIFF_HARD},
111 {8, 8, DIFF_EASY},
112 {8, 8, DIFF_HARD},
113 {12, 10, DIFF_EASY},
114 {12, 10, DIFF_HARD},
115 };
116
game_fetch_preset(int i,char ** name,game_params ** params)117 static bool game_fetch_preset(int i, char **name, game_params **params)
118 {
119 game_params *ret;
120 char str[80];
121
122 if (i < 0 || i >= lenof(slant_presets))
123 return false;
124
125 ret = snew(game_params);
126 *ret = slant_presets[i];
127
128 sprintf(str, "%dx%d %s", ret->w, ret->h, slant_diffnames[ret->diff]);
129
130 *name = dupstr(str);
131 *params = ret;
132 return true;
133 }
134
free_params(game_params * params)135 static void free_params(game_params *params)
136 {
137 sfree(params);
138 }
139
dup_params(const game_params * params)140 static game_params *dup_params(const game_params *params)
141 {
142 game_params *ret = snew(game_params);
143 *ret = *params; /* structure copy */
144 return ret;
145 }
146
decode_params(game_params * ret,char const * string)147 static void decode_params(game_params *ret, char const *string)
148 {
149 ret->w = ret->h = atoi(string);
150 while (*string && isdigit((unsigned char)*string)) string++;
151 if (*string == 'x') {
152 string++;
153 ret->h = atoi(string);
154 while (*string && isdigit((unsigned char)*string)) string++;
155 }
156 if (*string == 'd') {
157 int i;
158 string++;
159 for (i = 0; i < DIFFCOUNT; i++)
160 if (*string == slant_diffchars[i])
161 ret->diff = i;
162 if (*string) string++;
163 }
164 }
165
encode_params(const game_params * params,bool full)166 static char *encode_params(const game_params *params, bool full)
167 {
168 char data[256];
169
170 sprintf(data, "%dx%d", params->w, params->h);
171 if (full)
172 sprintf(data + strlen(data), "d%c", slant_diffchars[params->diff]);
173
174 return dupstr(data);
175 }
176
game_configure(const game_params * params)177 static config_item *game_configure(const game_params *params)
178 {
179 config_item *ret;
180 char buf[80];
181
182 ret = snewn(4, config_item);
183
184 ret[0].name = "Width";
185 ret[0].type = C_STRING;
186 sprintf(buf, "%d", params->w);
187 ret[0].u.string.sval = dupstr(buf);
188
189 ret[1].name = "Height";
190 ret[1].type = C_STRING;
191 sprintf(buf, "%d", params->h);
192 ret[1].u.string.sval = dupstr(buf);
193
194 ret[2].name = "Difficulty";
195 ret[2].type = C_CHOICES;
196 ret[2].u.choices.choicenames = DIFFCONFIG;
197 ret[2].u.choices.selected = params->diff;
198
199 ret[3].name = NULL;
200 ret[3].type = C_END;
201
202 return ret;
203 }
204
custom_params(const config_item * cfg)205 static game_params *custom_params(const config_item *cfg)
206 {
207 game_params *ret = snew(game_params);
208
209 ret->w = atoi(cfg[0].u.string.sval);
210 ret->h = atoi(cfg[1].u.string.sval);
211 ret->diff = cfg[2].u.choices.selected;
212
213 return ret;
214 }
215
validate_params(const game_params * params,bool full)216 static const char *validate_params(const game_params *params, bool full)
217 {
218 /*
219 * (At least at the time of writing this comment) The grid
220 * generator is actually capable of handling even zero grid
221 * dimensions without crashing. Puzzles with a zero-area grid
222 * are a bit boring, though, because they're already solved :-)
223 * And puzzles with a dimension of 1 can't be made Hard, which
224 * means the simplest thing is to forbid them altogether.
225 */
226
227 if (params->w < 2 || params->h < 2)
228 return "Width and height must both be at least two";
229
230 return NULL;
231 }
232
233 /*
234 * Scratch space for solver.
235 */
236 struct solver_scratch {
237 /*
238 * Disjoint set forest which tracks the connected sets of
239 * points.
240 */
241 int *connected;
242
243 /*
244 * Counts the number of possible exits from each connected set
245 * of points. (That is, the number of possible _simultaneous_
246 * exits: an unconnected point labelled 2 has an exit count of
247 * 2 even if all four possible edges are still under
248 * consideration.)
249 */
250 int *exits;
251
252 /*
253 * Tracks whether each connected set of points includes a
254 * border point.
255 */
256 bool *border;
257
258 /*
259 * Another disjoint set forest. This one tracks _squares_ which
260 * are known to slant in the same direction.
261 */
262 int *equiv;
263
264 /*
265 * Stores slash values which we know for an equivalence class.
266 * When we fill in a square, we set slashval[canonify(x)] to
267 * the same value as soln[x], so that we can then spot other
268 * squares equivalent to it and fill them in immediately via
269 * their known equivalence.
270 */
271 signed char *slashval;
272
273 /*
274 * Stores possible v-shapes. This array is w by h in size, but
275 * not every bit of every entry is meaningful. The bits mean:
276 *
277 * - bit 0 for a square means that that square and the one to
278 * its right might form a v-shape between them
279 * - bit 1 for a square means that that square and the one to
280 * its right might form a ^-shape between them
281 * - bit 2 for a square means that that square and the one
282 * below it might form a >-shape between them
283 * - bit 3 for a square means that that square and the one
284 * below it might form a <-shape between them
285 *
286 * Any starting 1 or 3 clue rules out four bits in this array
287 * immediately; a 2 clue propagates any ruled-out bit past it
288 * (if the two squares on one side of a 2 cannot be a v-shape,
289 * then neither can the two on the other side be the same
290 * v-shape); we can rule out further bits during play using
291 * partially filled 2 clues; whenever a pair of squares is
292 * known not to be _either_ kind of v-shape, we can mark them
293 * as equivalent.
294 */
295 unsigned char *vbitmap;
296
297 /*
298 * Useful to have this information automatically passed to
299 * solver subroutines. (This pointer is not dynamically
300 * allocated by new_scratch and free_scratch.)
301 */
302 const signed char *clues;
303 };
304
new_scratch(int w,int h)305 static struct solver_scratch *new_scratch(int w, int h)
306 {
307 int W = w+1, H = h+1;
308 struct solver_scratch *ret = snew(struct solver_scratch);
309 ret->connected = snewn(W*H, int);
310 ret->exits = snewn(W*H, int);
311 ret->border = snewn(W*H, bool);
312 ret->equiv = snewn(w*h, int);
313 ret->slashval = snewn(w*h, signed char);
314 ret->vbitmap = snewn(w*h, unsigned char);
315 return ret;
316 }
317
free_scratch(struct solver_scratch * sc)318 static void free_scratch(struct solver_scratch *sc)
319 {
320 sfree(sc->vbitmap);
321 sfree(sc->slashval);
322 sfree(sc->equiv);
323 sfree(sc->border);
324 sfree(sc->exits);
325 sfree(sc->connected);
326 sfree(sc);
327 }
328
329 /*
330 * Wrapper on dsf_merge() which updates the `exits' and `border'
331 * arrays.
332 */
merge_vertices(int * connected,struct solver_scratch * sc,int i,int j)333 static void merge_vertices(int *connected,
334 struct solver_scratch *sc, int i, int j)
335 {
336 int exits = -1;
337 bool border = false; /* initialise to placate optimiser */
338
339 if (sc) {
340 i = dsf_canonify(connected, i);
341 j = dsf_canonify(connected, j);
342
343 /*
344 * We have used one possible exit from each of the two
345 * classes. Thus, the viable exit count of the new class is
346 * the sum of the old exit counts minus two.
347 */
348 exits = sc->exits[i] + sc->exits[j] - 2;
349
350 border = sc->border[i] || sc->border[j];
351 }
352
353 dsf_merge(connected, i, j);
354
355 if (sc) {
356 i = dsf_canonify(connected, i);
357 sc->exits[i] = exits;
358 sc->border[i] = border;
359 }
360 }
361
362 /*
363 * Called when we have just blocked one way out of a particular
364 * point. If that point is a non-clue point (thus has a variable
365 * number of exits), we have therefore decreased its potential exit
366 * count, so we must decrement the exit count for the group as a
367 * whole.
368 */
decr_exits(struct solver_scratch * sc,int i)369 static void decr_exits(struct solver_scratch *sc, int i)
370 {
371 if (sc->clues[i] < 0) {
372 i = dsf_canonify(sc->connected, i);
373 sc->exits[i]--;
374 }
375 }
376
fill_square(int w,int h,int x,int y,int v,signed char * soln,int * connected,struct solver_scratch * sc)377 static void fill_square(int w, int h, int x, int y, int v,
378 signed char *soln,
379 int *connected, struct solver_scratch *sc)
380 {
381 int W = w+1 /*, H = h+1 */;
382
383 assert(x >= 0 && x < w && y >= 0 && y < h);
384
385 if (soln[y*w+x] != 0) {
386 return; /* do nothing */
387 }
388
389 #ifdef SOLVER_DIAGNOSTICS
390 if (verbose)
391 printf(" placing %c in %d,%d\n", v == -1 ? '\\' : '/', x, y);
392 #endif
393
394 soln[y*w+x] = v;
395
396 if (sc) {
397 int c = dsf_canonify(sc->equiv, y*w+x);
398 sc->slashval[c] = v;
399 }
400
401 if (v < 0) {
402 merge_vertices(connected, sc, y*W+x, (y+1)*W+(x+1));
403 if (sc) {
404 decr_exits(sc, y*W+(x+1));
405 decr_exits(sc, (y+1)*W+x);
406 }
407 } else {
408 merge_vertices(connected, sc, y*W+(x+1), (y+1)*W+x);
409 if (sc) {
410 decr_exits(sc, y*W+x);
411 decr_exits(sc, (y+1)*W+(x+1));
412 }
413 }
414 }
415
vbitmap_clear(int w,int h,struct solver_scratch * sc,int x,int y,int vbits,const char * reason,...)416 static bool vbitmap_clear(int w, int h, struct solver_scratch *sc,
417 int x, int y, int vbits, const char *reason, ...)
418 {
419 bool done_something = false;
420 int vbit;
421
422 for (vbit = 1; vbit <= 8; vbit <<= 1)
423 if (vbits & sc->vbitmap[y*w+x] & vbit) {
424 done_something = true;
425 #ifdef SOLVER_DIAGNOSTICS
426 if (verbose) {
427 va_list ap;
428
429 printf("ruling out %c shape at (%d,%d)-(%d,%d) (",
430 "!v^!>!!!<"[vbit], x, y,
431 x+((vbit&0x3)!=0), y+((vbit&0xC)!=0));
432
433 va_start(ap, reason);
434 vprintf(reason, ap);
435 va_end(ap);
436
437 printf(")\n");
438 }
439 #endif
440 sc->vbitmap[y*w+x] &= ~vbit;
441 }
442
443 return done_something;
444 }
445
446 /*
447 * Solver. Returns 0 for impossibility, 1 for success, 2 for
448 * ambiguity or failure to converge.
449 */
slant_solve(int w,int h,const signed char * clues,signed char * soln,struct solver_scratch * sc,int difficulty)450 static int slant_solve(int w, int h, const signed char *clues,
451 signed char *soln, struct solver_scratch *sc,
452 int difficulty)
453 {
454 int W = w+1, H = h+1;
455 int x, y, i, j;
456 bool done_something;
457
458 /*
459 * Clear the output.
460 */
461 memset(soln, 0, w*h);
462
463 sc->clues = clues;
464
465 /*
466 * Establish a disjoint set forest for tracking connectedness
467 * between grid points.
468 */
469 dsf_init(sc->connected, W*H);
470
471 /*
472 * Establish a disjoint set forest for tracking which squares
473 * are known to slant in the same direction.
474 */
475 dsf_init(sc->equiv, w*h);
476
477 /*
478 * Clear the slashval array.
479 */
480 memset(sc->slashval, 0, w*h);
481
482 /*
483 * Set up the vbitmap array. Initially all types of v are possible.
484 */
485 memset(sc->vbitmap, 0xF, w*h);
486
487 /*
488 * Initialise the `exits' and `border' arrays. These are used
489 * to do second-order loop avoidance: the dual of the no loops
490 * constraint is that every point must be somehow connected to
491 * the border of the grid (otherwise there would be a solid
492 * loop around it which prevented this).
493 *
494 * I define a `dead end' to be a connected group of points
495 * which contains no border point, and which can form at most
496 * one new connection outside itself. Then I forbid placing an
497 * edge so that it connects together two dead-end groups, since
498 * this would yield a non-border-connected isolated subgraph
499 * with no further scope to extend it.
500 */
501 for (y = 0; y < H; y++)
502 for (x = 0; x < W; x++) {
503 if (y == 0 || y == H-1 || x == 0 || x == W-1)
504 sc->border[y*W+x] = true;
505 else
506 sc->border[y*W+x] = false;
507
508 if (clues[y*W+x] < 0)
509 sc->exits[y*W+x] = 4;
510 else
511 sc->exits[y*W+x] = clues[y*W+x];
512 }
513
514 /*
515 * Repeatedly try to deduce something until we can't.
516 */
517 do {
518 done_something = false;
519
520 /*
521 * Any clue point with the number of remaining lines equal
522 * to zero or to the number of remaining undecided
523 * neighbouring squares can be filled in completely.
524 */
525 for (y = 0; y < H; y++)
526 for (x = 0; x < W; x++) {
527 struct {
528 int pos, slash;
529 } neighbours[4];
530 int nneighbours;
531 int nu, nl, c, s, eq, eq2, last, meq, mj1, mj2;
532
533 if ((c = clues[y*W+x]) < 0)
534 continue;
535
536 /*
537 * We have a clue point. Start by listing its
538 * neighbouring squares, in order around the point,
539 * together with the type of slash that would be
540 * required in that square to connect to the point.
541 */
542 nneighbours = 0;
543 if (x > 0 && y > 0) {
544 neighbours[nneighbours].pos = (y-1)*w+(x-1);
545 neighbours[nneighbours].slash = -1;
546 nneighbours++;
547 }
548 if (x > 0 && y < h) {
549 neighbours[nneighbours].pos = y*w+(x-1);
550 neighbours[nneighbours].slash = +1;
551 nneighbours++;
552 }
553 if (x < w && y < h) {
554 neighbours[nneighbours].pos = y*w+x;
555 neighbours[nneighbours].slash = -1;
556 nneighbours++;
557 }
558 if (x < w && y > 0) {
559 neighbours[nneighbours].pos = (y-1)*w+x;
560 neighbours[nneighbours].slash = +1;
561 nneighbours++;
562 }
563
564 /*
565 * Count up the number of undecided neighbours, and
566 * also the number of lines already present.
567 *
568 * If we're not on DIFF_EASY, then in this loop we
569 * also track whether we've seen two adjacent empty
570 * squares belonging to the same equivalence class
571 * (meaning they have the same type of slash). If
572 * so, we count them jointly as one line.
573 */
574 nu = 0;
575 nl = c;
576 last = neighbours[nneighbours-1].pos;
577 if (soln[last] == 0)
578 eq = dsf_canonify(sc->equiv, last);
579 else
580 eq = -1;
581 meq = mj1 = mj2 = -1;
582 for (i = 0; i < nneighbours; i++) {
583 j = neighbours[i].pos;
584 s = neighbours[i].slash;
585 if (soln[j] == 0) {
586 nu++; /* undecided */
587 if (meq < 0 && difficulty > DIFF_EASY) {
588 eq2 = dsf_canonify(sc->equiv, j);
589 if (eq == eq2 && last != j) {
590 /*
591 * We've found an equivalent pair.
592 * Mark it. This also inhibits any
593 * further equivalence tracking
594 * around this square, since we can
595 * only handle one pair (and in
596 * particular we want to avoid
597 * being misled by two overlapping
598 * equivalence pairs).
599 */
600 meq = eq;
601 mj1 = last;
602 mj2 = j;
603 nl--; /* count one line */
604 nu -= 2; /* and lose two undecideds */
605 } else
606 eq = eq2;
607 }
608 } else {
609 eq = -1;
610 if (soln[j] == s)
611 nl--; /* here's a line */
612 }
613 last = j;
614 }
615
616 /*
617 * Check the counts.
618 */
619 if (nl < 0 || nl > nu) {
620 /*
621 * No consistent value for this at all!
622 */
623 #ifdef SOLVER_DIAGNOSTICS
624 if (verbose)
625 printf("need %d / %d lines around clue point at %d,%d!\n",
626 nl, nu, x, y);
627 #endif
628 return 0; /* impossible */
629 }
630
631 if (nu > 0 && (nl == 0 || nl == nu)) {
632 #ifdef SOLVER_DIAGNOSTICS
633 if (verbose) {
634 if (meq >= 0)
635 printf("partially (since %d,%d == %d,%d) ",
636 mj1%w, mj1/w, mj2%w, mj2/w);
637 printf("%s around clue point at %d,%d\n",
638 nl ? "filling" : "emptying", x, y);
639 }
640 #endif
641 for (i = 0; i < nneighbours; i++) {
642 j = neighbours[i].pos;
643 s = neighbours[i].slash;
644 if (soln[j] == 0 && j != mj1 && j != mj2)
645 fill_square(w, h, j%w, j/w, (nl ? s : -s), soln,
646 sc->connected, sc);
647 }
648
649 done_something = true;
650 } else if (nu == 2 && nl == 1 && difficulty > DIFF_EASY) {
651 /*
652 * If we have precisely two undecided squares
653 * and precisely one line to place between
654 * them, _and_ those squares are adjacent, then
655 * we can mark them as equivalent to one
656 * another.
657 *
658 * This even applies if meq >= 0: if we have a
659 * 2 clue point and two of its neighbours are
660 * already marked equivalent, we can indeed
661 * mark the other two as equivalent.
662 *
663 * We don't bother with this on DIFF_EASY,
664 * since we wouldn't have used the results
665 * anyway.
666 */
667 last = -1;
668 for (i = 0; i < nneighbours; i++) {
669 j = neighbours[i].pos;
670 if (soln[j] == 0 && j != mj1 && j != mj2) {
671 if (last < 0)
672 last = i;
673 else if (last == i-1 || (last == 0 && i == 3))
674 break; /* found a pair */
675 }
676 }
677 if (i < nneighbours) {
678 int sv1, sv2;
679
680 assert(last >= 0);
681 /*
682 * neighbours[last] and neighbours[i] are
683 * the pair. Mark them equivalent.
684 */
685 #ifdef SOLVER_DIAGNOSTICS
686 if (verbose) {
687 if (meq >= 0)
688 printf("since %d,%d == %d,%d, ",
689 mj1%w, mj1/w, mj2%w, mj2/w);
690 }
691 #endif
692 mj1 = neighbours[last].pos;
693 mj2 = neighbours[i].pos;
694 #ifdef SOLVER_DIAGNOSTICS
695 if (verbose)
696 printf("clue point at %d,%d implies %d,%d == %d,"
697 "%d\n", x, y, mj1%w, mj1/w, mj2%w, mj2/w);
698 #endif
699 mj1 = dsf_canonify(sc->equiv, mj1);
700 sv1 = sc->slashval[mj1];
701 mj2 = dsf_canonify(sc->equiv, mj2);
702 sv2 = sc->slashval[mj2];
703 if (sv1 != 0 && sv2 != 0 && sv1 != sv2) {
704 #ifdef SOLVER_DIAGNOSTICS
705 if (verbose)
706 printf("merged two equivalence classes with"
707 " different slash values!\n");
708 #endif
709 return 0;
710 }
711 sv1 = sv1 ? sv1 : sv2;
712 dsf_merge(sc->equiv, mj1, mj2);
713 mj1 = dsf_canonify(sc->equiv, mj1);
714 sc->slashval[mj1] = sv1;
715 }
716 }
717 }
718
719 if (done_something)
720 continue;
721
722 /*
723 * Failing that, we now apply the second condition, which
724 * is that no square may be filled in such a way as to form
725 * a loop. Also in this loop (since it's over squares
726 * rather than points), we check slashval to see if we've
727 * already filled in another square in the same equivalence
728 * class.
729 *
730 * The slashval check is disabled on DIFF_EASY, as is dead
731 * end avoidance. Only _immediate_ loop avoidance remains.
732 */
733 for (y = 0; y < h; y++)
734 for (x = 0; x < w; x++) {
735 bool fs, bs;
736 int v, c1, c2;
737 #ifdef SOLVER_DIAGNOSTICS
738 const char *reason = "<internal error>";
739 #endif
740
741 if (soln[y*w+x])
742 continue; /* got this one already */
743
744 fs = false;
745 bs = false;
746
747 if (difficulty > DIFF_EASY)
748 v = sc->slashval[dsf_canonify(sc->equiv, y*w+x)];
749 else
750 v = 0;
751
752 /*
753 * Try to rule out connectivity between (x,y) and
754 * (x+1,y+1); if successful, we will deduce that we
755 * must have a forward slash.
756 */
757 c1 = dsf_canonify(sc->connected, y*W+x);
758 c2 = dsf_canonify(sc->connected, (y+1)*W+(x+1));
759 if (c1 == c2) {
760 fs = true;
761 #ifdef SOLVER_DIAGNOSTICS
762 reason = "simple loop avoidance";
763 #endif
764 }
765 if (difficulty > DIFF_EASY &&
766 !sc->border[c1] && !sc->border[c2] &&
767 sc->exits[c1] <= 1 && sc->exits[c2] <= 1) {
768 fs = true;
769 #ifdef SOLVER_DIAGNOSTICS
770 reason = "dead end avoidance";
771 #endif
772 }
773 if (v == +1) {
774 fs = true;
775 #ifdef SOLVER_DIAGNOSTICS
776 reason = "equivalence to an already filled square";
777 #endif
778 }
779
780 /*
781 * Now do the same between (x+1,y) and (x,y+1), to
782 * see if we are required to have a backslash.
783 */
784 c1 = dsf_canonify(sc->connected, y*W+(x+1));
785 c2 = dsf_canonify(sc->connected, (y+1)*W+x);
786 if (c1 == c2) {
787 bs = true;
788 #ifdef SOLVER_DIAGNOSTICS
789 reason = "simple loop avoidance";
790 #endif
791 }
792 if (difficulty > DIFF_EASY &&
793 !sc->border[c1] && !sc->border[c2] &&
794 sc->exits[c1] <= 1 && sc->exits[c2] <= 1) {
795 bs = true;
796 #ifdef SOLVER_DIAGNOSTICS
797 reason = "dead end avoidance";
798 #endif
799 }
800 if (v == -1) {
801 bs = true;
802 #ifdef SOLVER_DIAGNOSTICS
803 reason = "equivalence to an already filled square";
804 #endif
805 }
806
807 if (fs && bs) {
808 /*
809 * No consistent value for this at all!
810 */
811 #ifdef SOLVER_DIAGNOSTICS
812 if (verbose)
813 printf("%d,%d has no consistent slash!\n", x, y);
814 #endif
815 return 0; /* impossible */
816 }
817
818 if (fs) {
819 #ifdef SOLVER_DIAGNOSTICS
820 if (verbose)
821 printf("employing %s\n", reason);
822 #endif
823 fill_square(w, h, x, y, +1, soln, sc->connected, sc);
824 done_something = true;
825 } else if (bs) {
826 #ifdef SOLVER_DIAGNOSTICS
827 if (verbose)
828 printf("employing %s\n", reason);
829 #endif
830 fill_square(w, h, x, y, -1, soln, sc->connected, sc);
831 done_something = true;
832 }
833 }
834
835 if (done_something)
836 continue;
837
838 /*
839 * Now see what we can do with the vbitmap array. All
840 * vbitmap deductions are disabled at Easy level.
841 */
842 if (difficulty <= DIFF_EASY)
843 continue;
844
845 for (y = 0; y < h; y++)
846 for (x = 0; x < w; x++) {
847 int s, c;
848
849 /*
850 * Any line already placed in a square must rule
851 * out any type of v which contradicts it.
852 */
853 if ((s = soln[y*w+x]) != 0) {
854 if (x > 0)
855 done_something |=
856 vbitmap_clear(w, h, sc, x-1, y, (s < 0 ? 0x1 : 0x2),
857 "contradicts known edge at (%d,%d)",x,y);
858 if (x+1 < w)
859 done_something |=
860 vbitmap_clear(w, h, sc, x, y, (s < 0 ? 0x2 : 0x1),
861 "contradicts known edge at (%d,%d)",x,y);
862 if (y > 0)
863 done_something |=
864 vbitmap_clear(w, h, sc, x, y-1, (s < 0 ? 0x4 : 0x8),
865 "contradicts known edge at (%d,%d)",x,y);
866 if (y+1 < h)
867 done_something |=
868 vbitmap_clear(w, h, sc, x, y, (s < 0 ? 0x8 : 0x4),
869 "contradicts known edge at (%d,%d)",x,y);
870 }
871
872 /*
873 * If both types of v are ruled out for a pair of
874 * adjacent squares, mark them as equivalent.
875 */
876 if (x+1 < w && !(sc->vbitmap[y*w+x] & 0x3)) {
877 int n1 = y*w+x, n2 = y*w+(x+1);
878 if (dsf_canonify(sc->equiv, n1) !=
879 dsf_canonify(sc->equiv, n2)) {
880 dsf_merge(sc->equiv, n1, n2);
881 done_something = true;
882 #ifdef SOLVER_DIAGNOSTICS
883 if (verbose)
884 printf("(%d,%d) and (%d,%d) must be equivalent"
885 " because both v-shapes are ruled out\n",
886 x, y, x+1, y);
887 #endif
888 }
889 }
890 if (y+1 < h && !(sc->vbitmap[y*w+x] & 0xC)) {
891 int n1 = y*w+x, n2 = (y+1)*w+x;
892 if (dsf_canonify(sc->equiv, n1) !=
893 dsf_canonify(sc->equiv, n2)) {
894 dsf_merge(sc->equiv, n1, n2);
895 done_something = true;
896 #ifdef SOLVER_DIAGNOSTICS
897 if (verbose)
898 printf("(%d,%d) and (%d,%d) must be equivalent"
899 " because both v-shapes are ruled out\n",
900 x, y, x, y+1);
901 #endif
902 }
903 }
904
905 /*
906 * The remaining work in this loop only works
907 * around non-edge clue points.
908 */
909 if (y == 0 || x == 0)
910 continue;
911 if ((c = clues[y*W+x]) < 0)
912 continue;
913
914 /*
915 * x,y marks a clue point not on the grid edge. See
916 * if this clue point allows us to rule out any v
917 * shapes.
918 */
919
920 if (c == 1) {
921 /*
922 * A 1 clue can never have any v shape pointing
923 * at it.
924 */
925 done_something |=
926 vbitmap_clear(w, h, sc, x-1, y-1, 0x5,
927 "points at 1 clue at (%d,%d)", x, y);
928 done_something |=
929 vbitmap_clear(w, h, sc, x-1, y, 0x2,
930 "points at 1 clue at (%d,%d)", x, y);
931 done_something |=
932 vbitmap_clear(w, h, sc, x, y-1, 0x8,
933 "points at 1 clue at (%d,%d)", x, y);
934 } else if (c == 3) {
935 /*
936 * A 3 clue can never have any v shape pointing
937 * away from it.
938 */
939 done_something |=
940 vbitmap_clear(w, h, sc, x-1, y-1, 0xA,
941 "points away from 3 clue at (%d,%d)", x, y);
942 done_something |=
943 vbitmap_clear(w, h, sc, x-1, y, 0x1,
944 "points away from 3 clue at (%d,%d)", x, y);
945 done_something |=
946 vbitmap_clear(w, h, sc, x, y-1, 0x4,
947 "points away from 3 clue at (%d,%d)", x, y);
948 } else if (c == 2) {
949 /*
950 * If a 2 clue has any kind of v ruled out on
951 * one side of it, the same v is ruled out on
952 * the other side.
953 */
954 done_something |=
955 vbitmap_clear(w, h, sc, x-1, y-1,
956 (sc->vbitmap[(y )*w+(x-1)] & 0x3) ^ 0x3,
957 "propagated by 2 clue at (%d,%d)", x, y);
958 done_something |=
959 vbitmap_clear(w, h, sc, x-1, y-1,
960 (sc->vbitmap[(y-1)*w+(x )] & 0xC) ^ 0xC,
961 "propagated by 2 clue at (%d,%d)", x, y);
962 done_something |=
963 vbitmap_clear(w, h, sc, x-1, y,
964 (sc->vbitmap[(y-1)*w+(x-1)] & 0x3) ^ 0x3,
965 "propagated by 2 clue at (%d,%d)", x, y);
966 done_something |=
967 vbitmap_clear(w, h, sc, x, y-1,
968 (sc->vbitmap[(y-1)*w+(x-1)] & 0xC) ^ 0xC,
969 "propagated by 2 clue at (%d,%d)", x, y);
970 }
971
972 #undef CLEARBITS
973
974 }
975
976 } while (done_something);
977
978 /*
979 * Solver can make no more progress. See if the grid is full.
980 */
981 for (i = 0; i < w*h; i++)
982 if (!soln[i])
983 return 2; /* failed to converge */
984 return 1; /* success */
985 }
986
987 /*
988 * Filled-grid generator.
989 */
slant_generate(int w,int h,signed char * soln,random_state * rs)990 static void slant_generate(int w, int h, signed char *soln, random_state *rs)
991 {
992 int W = w+1, H = h+1;
993 int x, y, i;
994 int *connected, *indices;
995
996 /*
997 * Clear the output.
998 */
999 memset(soln, 0, w*h);
1000
1001 /*
1002 * Establish a disjoint set forest for tracking connectedness
1003 * between grid points.
1004 */
1005 connected = snew_dsf(W*H);
1006
1007 /*
1008 * Prepare a list of the squares in the grid, and fill them in
1009 * in a random order.
1010 */
1011 indices = snewn(w*h, int);
1012 for (i = 0; i < w*h; i++)
1013 indices[i] = i;
1014 shuffle(indices, w*h, sizeof(*indices), rs);
1015
1016 /*
1017 * Fill in each one in turn.
1018 */
1019 for (i = 0; i < w*h; i++) {
1020 bool fs, bs;
1021 int v;
1022
1023 y = indices[i] / w;
1024 x = indices[i] % w;
1025
1026 fs = (dsf_canonify(connected, y*W+x) ==
1027 dsf_canonify(connected, (y+1)*W+(x+1)));
1028 bs = (dsf_canonify(connected, (y+1)*W+x) ==
1029 dsf_canonify(connected, y*W+(x+1)));
1030
1031 /*
1032 * It isn't possible to get into a situation where we
1033 * aren't allowed to place _either_ type of slash in a
1034 * square. Thus, filled-grid generation never has to
1035 * backtrack.
1036 *
1037 * Proof (thanks to Gareth Taylor):
1038 *
1039 * If it were possible, it would have to be because there
1040 * was an existing path (not using this square) between the
1041 * top-left and bottom-right corners of this square, and
1042 * another between the other two. These two paths would
1043 * have to cross at some point.
1044 *
1045 * Obviously they can't cross in the middle of a square, so
1046 * they must cross by sharing a point in common. But this
1047 * isn't possible either: if you chessboard-colour all the
1048 * points on the grid, you find that any continuous
1049 * diagonal path is entirely composed of points of the same
1050 * colour. And one of our two hypothetical paths is between
1051 * two black points, and the other is between two white
1052 * points - therefore they can have no point in common. []
1053 */
1054 assert(!(fs && bs));
1055
1056 v = fs ? +1 : bs ? -1 : 2 * random_upto(rs, 2) - 1;
1057 fill_square(w, h, x, y, v, soln, connected, NULL);
1058 }
1059
1060 sfree(indices);
1061 sfree(connected);
1062 }
1063
new_game_desc(const game_params * params,random_state * rs,char ** aux,bool interactive)1064 static char *new_game_desc(const game_params *params, random_state *rs,
1065 char **aux, bool interactive)
1066 {
1067 int w = params->w, h = params->h, W = w+1, H = h+1;
1068 signed char *soln, *tmpsoln, *clues;
1069 int *clueindices;
1070 struct solver_scratch *sc;
1071 int x, y, v, i, j;
1072 char *desc;
1073
1074 soln = snewn(w*h, signed char);
1075 tmpsoln = snewn(w*h, signed char);
1076 clues = snewn(W*H, signed char);
1077 clueindices = snewn(W*H, int);
1078 sc = new_scratch(w, h);
1079
1080 do {
1081 /*
1082 * Create the filled grid.
1083 */
1084 slant_generate(w, h, soln, rs);
1085
1086 /*
1087 * Fill in the complete set of clues.
1088 */
1089 for (y = 0; y < H; y++)
1090 for (x = 0; x < W; x++) {
1091 v = 0;
1092
1093 if (x > 0 && y > 0 && soln[(y-1)*w+(x-1)] == -1) v++;
1094 if (x > 0 && y < h && soln[y*w+(x-1)] == +1) v++;
1095 if (x < w && y > 0 && soln[(y-1)*w+x] == +1) v++;
1096 if (x < w && y < h && soln[y*w+x] == -1) v++;
1097
1098 clues[y*W+x] = v;
1099 }
1100
1101 /*
1102 * With all clue points filled in, all puzzles are easy: we can
1103 * simply process the clue points in lexicographic order, and
1104 * at each clue point we will always have at most one square
1105 * undecided, which we can then fill in uniquely.
1106 */
1107 assert(slant_solve(w, h, clues, tmpsoln, sc, DIFF_EASY) == 1);
1108
1109 /*
1110 * Remove as many clues as possible while retaining solubility.
1111 *
1112 * In DIFF_HARD mode, we prioritise the removal of obvious
1113 * starting points (4s, 0s, border 2s and corner 1s), on
1114 * the grounds that having as few of these as possible
1115 * seems like a good thing. In particular, we can often get
1116 * away without _any_ completely obvious starting points,
1117 * which is even better.
1118 */
1119 for (i = 0; i < W*H; i++)
1120 clueindices[i] = i;
1121 shuffle(clueindices, W*H, sizeof(*clueindices), rs);
1122 for (j = 0; j < 2; j++) {
1123 for (i = 0; i < W*H; i++) {
1124 int pass;
1125 bool yb, xb;
1126
1127 y = clueindices[i] / W;
1128 x = clueindices[i] % W;
1129 v = clues[y*W+x];
1130
1131 /*
1132 * Identify which pass we should process this point
1133 * in. If it's an obvious start point, _or_ we're
1134 * in DIFF_EASY, then it goes in pass 0; otherwise
1135 * pass 1.
1136 */
1137 xb = (x == 0 || x == W-1);
1138 yb = (y == 0 || y == H-1);
1139 if (params->diff == DIFF_EASY || v == 4 || v == 0 ||
1140 (v == 2 && (xb||yb)) || (v == 1 && xb && yb))
1141 pass = 0;
1142 else
1143 pass = 1;
1144
1145 if (pass == j) {
1146 clues[y*W+x] = -1;
1147 if (slant_solve(w, h, clues, tmpsoln, sc,
1148 params->diff) != 1)
1149 clues[y*W+x] = v; /* put it back */
1150 }
1151 }
1152 }
1153
1154 /*
1155 * And finally, verify that the grid is of _at least_ the
1156 * requested difficulty, by running the solver one level
1157 * down and verifying that it can't manage it.
1158 */
1159 } while (params->diff > 0 &&
1160 slant_solve(w, h, clues, tmpsoln, sc, params->diff - 1) <= 1);
1161
1162 /*
1163 * Now we have the clue set as it will be presented to the
1164 * user. Encode it in a game desc.
1165 */
1166 {
1167 char *p;
1168 int run, i;
1169
1170 desc = snewn(W*H+1, char);
1171 p = desc;
1172 run = 0;
1173 for (i = 0; i <= W*H; i++) {
1174 int n = (i < W*H ? clues[i] : -2);
1175
1176 if (n == -1)
1177 run++;
1178 else {
1179 if (run) {
1180 while (run > 0) {
1181 int c = 'a' - 1 + run;
1182 if (run > 26)
1183 c = 'z';
1184 *p++ = c;
1185 run -= c - ('a' - 1);
1186 }
1187 }
1188 if (n >= 0)
1189 *p++ = '0' + n;
1190 run = 0;
1191 }
1192 }
1193 assert(p - desc <= W*H);
1194 *p++ = '\0';
1195 desc = sresize(desc, p - desc, char);
1196 }
1197
1198 /*
1199 * Encode the solution as an aux_info.
1200 */
1201 {
1202 char *auxbuf;
1203 *aux = auxbuf = snewn(w*h+1, char);
1204 for (i = 0; i < w*h; i++)
1205 auxbuf[i] = soln[i] < 0 ? '\\' : '/';
1206 auxbuf[w*h] = '\0';
1207 }
1208
1209 free_scratch(sc);
1210 sfree(clueindices);
1211 sfree(clues);
1212 sfree(tmpsoln);
1213 sfree(soln);
1214
1215 return desc;
1216 }
1217
validate_desc(const game_params * params,const char * desc)1218 static const char *validate_desc(const game_params *params, const char *desc)
1219 {
1220 int w = params->w, h = params->h, W = w+1, H = h+1;
1221 int area = W*H;
1222 int squares = 0;
1223
1224 while (*desc) {
1225 int n = *desc++;
1226 if (n >= 'a' && n <= 'z') {
1227 squares += n - 'a' + 1;
1228 } else if (n >= '0' && n <= '4') {
1229 squares++;
1230 } else
1231 return "Invalid character in game description";
1232 }
1233
1234 if (squares < area)
1235 return "Not enough data to fill grid";
1236
1237 if (squares > area)
1238 return "Too much data to fit in grid";
1239
1240 return NULL;
1241 }
1242
new_game(midend * me,const game_params * params,const char * desc)1243 static game_state *new_game(midend *me, const game_params *params,
1244 const char *desc)
1245 {
1246 int w = params->w, h = params->h, W = w+1, H = h+1;
1247 game_state *state = snew(game_state);
1248 int area = W*H;
1249 int squares = 0;
1250
1251 state->p = *params;
1252 state->soln = snewn(w*h, signed char);
1253 memset(state->soln, 0, w*h);
1254 state->completed = state->used_solve = false;
1255 state->errors = snewn(W*H, unsigned char);
1256 memset(state->errors, 0, W*H);
1257
1258 state->clues = snew(game_clues);
1259 state->clues->w = w;
1260 state->clues->h = h;
1261 state->clues->clues = snewn(W*H, signed char);
1262 state->clues->refcount = 1;
1263 state->clues->tmpdsf = snewn(W*H*2+W+H, int);
1264 memset(state->clues->clues, -1, W*H);
1265 while (*desc) {
1266 int n = *desc++;
1267 if (n >= 'a' && n <= 'z') {
1268 squares += n - 'a' + 1;
1269 } else if (n >= '0' && n <= '4') {
1270 state->clues->clues[squares++] = n - '0';
1271 } else
1272 assert(!"can't get here");
1273 }
1274 assert(squares == area);
1275
1276 return state;
1277 }
1278
dup_game(const game_state * state)1279 static game_state *dup_game(const game_state *state)
1280 {
1281 int w = state->p.w, h = state->p.h, W = w+1, H = h+1;
1282 game_state *ret = snew(game_state);
1283
1284 ret->p = state->p;
1285 ret->clues = state->clues;
1286 ret->clues->refcount++;
1287 ret->completed = state->completed;
1288 ret->used_solve = state->used_solve;
1289
1290 ret->soln = snewn(w*h, signed char);
1291 memcpy(ret->soln, state->soln, w*h);
1292
1293 ret->errors = snewn(W*H, unsigned char);
1294 memcpy(ret->errors, state->errors, W*H);
1295
1296 return ret;
1297 }
1298
free_game(game_state * state)1299 static void free_game(game_state *state)
1300 {
1301 sfree(state->errors);
1302 sfree(state->soln);
1303 assert(state->clues);
1304 if (--state->clues->refcount <= 0) {
1305 sfree(state->clues->clues);
1306 sfree(state->clues->tmpdsf);
1307 sfree(state->clues);
1308 }
1309 sfree(state);
1310 }
1311
1312 /*
1313 * Utility function to return the current degree of a vertex. If
1314 * `anti' is set, it returns the number of filled-in edges
1315 * surrounding the point which _don't_ connect to it; thus 4 minus
1316 * its anti-degree is the maximum degree it could have if all the
1317 * empty spaces around it were filled in.
1318 *
1319 * (Yes, _4_ minus its anti-degree even if it's a border vertex.)
1320 *
1321 * If ret > 0, *sx and *sy are set to the coordinates of one of the
1322 * squares that contributed to it.
1323 */
vertex_degree(int w,int h,signed char * soln,int x,int y,bool anti,int * sx,int * sy)1324 static int vertex_degree(int w, int h, signed char *soln, int x, int y,
1325 bool anti, int *sx, int *sy)
1326 {
1327 int ret = 0;
1328
1329 assert(x >= 0 && x <= w && y >= 0 && y <= h);
1330 if (x > 0 && y > 0 && soln[(y-1)*w+(x-1)] - anti < 0) {
1331 if (sx) *sx = x-1;
1332 if (sy) *sy = y-1;
1333 ret++;
1334 }
1335 if (x > 0 && y < h && soln[y*w+(x-1)] + anti > 0) {
1336 if (sx) *sx = x-1;
1337 if (sy) *sy = y;
1338 ret++;
1339 }
1340 if (x < w && y > 0 && soln[(y-1)*w+x] + anti > 0) {
1341 if (sx) *sx = x;
1342 if (sy) *sy = y-1;
1343 ret++;
1344 }
1345 if (x < w && y < h && soln[y*w+x] - anti < 0) {
1346 if (sx) *sx = x;
1347 if (sy) *sy = y;
1348 ret++;
1349 }
1350
1351 return anti ? 4 - ret : ret;
1352 }
1353
1354 struct slant_neighbour_ctx {
1355 const game_state *state;
1356 int i, n, neighbours[4];
1357 };
slant_neighbour(int vertex,void * vctx)1358 static int slant_neighbour(int vertex, void *vctx)
1359 {
1360 struct slant_neighbour_ctx *ctx = (struct slant_neighbour_ctx *)vctx;
1361
1362 if (vertex >= 0) {
1363 int w = ctx->state->p.w, h = ctx->state->p.h, W = w+1;
1364 int x = vertex % W, y = vertex / W;
1365 ctx->n = ctx->i = 0;
1366 if (x < w && y < h && ctx->state->soln[y*w+x] < 0)
1367 ctx->neighbours[ctx->n++] = (y+1)*W+(x+1);
1368 if (x > 0 && y > 0 && ctx->state->soln[(y-1)*w+(x-1)] < 0)
1369 ctx->neighbours[ctx->n++] = (y-1)*W+(x-1);
1370 if (x > 0 && y < h && ctx->state->soln[y*w+(x-1)] > 0)
1371 ctx->neighbours[ctx->n++] = (y+1)*W+(x-1);
1372 if (x < w && y > 0 && ctx->state->soln[(y-1)*w+x] > 0)
1373 ctx->neighbours[ctx->n++] = (y-1)*W+(x+1);
1374 }
1375
1376 if (ctx->i < ctx->n)
1377 return ctx->neighbours[ctx->i++];
1378 else
1379 return -1;
1380 }
1381
check_completion(game_state * state)1382 static bool check_completion(game_state *state)
1383 {
1384 int w = state->p.w, h = state->p.h, W = w+1, H = h+1;
1385 int x, y;
1386 bool err = false;
1387
1388 memset(state->errors, 0, W*H);
1389
1390 /*
1391 * Detect and error-highlight loops in the grid.
1392 */
1393 {
1394 struct findloopstate *fls = findloop_new_state(W*H);
1395 struct slant_neighbour_ctx ctx;
1396 ctx.state = state;
1397
1398 if (findloop_run(fls, W*H, slant_neighbour, &ctx))
1399 err = true;
1400 for (y = 0; y < h; y++) {
1401 for (x = 0; x < w; x++) {
1402 int u, v;
1403 if (state->soln[y*w+x] == 0) {
1404 continue;
1405 } else if (state->soln[y*w+x] > 0) {
1406 u = y*W+(x+1);
1407 v = (y+1)*W+x;
1408 } else {
1409 u = (y+1)*W+(x+1);
1410 v = y*W+x;
1411 }
1412 if (findloop_is_loop_edge(fls, u, v))
1413 state->errors[y*W+x] |= ERR_SQUARE;
1414 }
1415 }
1416
1417 findloop_free_state(fls);
1418 }
1419
1420 /*
1421 * Now go through and check the degree of each clue vertex, and
1422 * mark it with ERR_VERTEX if it cannot be fulfilled.
1423 */
1424 for (y = 0; y < H; y++)
1425 for (x = 0; x < W; x++) {
1426 int c;
1427
1428 if ((c = state->clues->clues[y*W+x]) < 0)
1429 continue;
1430
1431 /*
1432 * Check to see if there are too many connections to
1433 * this vertex _or_ too many non-connections. Either is
1434 * grounds for marking the vertex as erroneous.
1435 */
1436 if (vertex_degree(w, h, state->soln, x, y,
1437 false, NULL, NULL) > c ||
1438 vertex_degree(w, h, state->soln, x, y,
1439 true, NULL, NULL) > 4-c) {
1440 state->errors[y*W+x] |= ERR_VERTEX;
1441 err = true;
1442 }
1443 }
1444
1445 /*
1446 * Now our actual victory condition is that (a) none of the
1447 * above code marked anything as erroneous, and (b) every
1448 * square has an edge in it.
1449 */
1450
1451 if (err)
1452 return false;
1453
1454 for (y = 0; y < h; y++)
1455 for (x = 0; x < w; x++)
1456 if (state->soln[y*w+x] == 0)
1457 return false;
1458
1459 return true;
1460 }
1461
solve_game(const game_state * state,const game_state * currstate,const char * aux,const char ** error)1462 static char *solve_game(const game_state *state, const game_state *currstate,
1463 const char *aux, const char **error)
1464 {
1465 int w = state->p.w, h = state->p.h;
1466 signed char *soln;
1467 int bs, ret;
1468 bool free_soln = false;
1469 char *move, buf[80];
1470 int movelen, movesize;
1471 int x, y;
1472
1473 if (aux) {
1474 /*
1475 * If we already have the solution, save ourselves some
1476 * time.
1477 */
1478 soln = (signed char *)aux;
1479 bs = (signed char)'\\';
1480 free_soln = false;
1481 } else {
1482 struct solver_scratch *sc = new_scratch(w, h);
1483 soln = snewn(w*h, signed char);
1484 bs = -1;
1485 ret = slant_solve(w, h, state->clues->clues, soln, sc, DIFF_HARD);
1486 free_scratch(sc);
1487 if (ret != 1) {
1488 sfree(soln);
1489 if (ret == 0)
1490 *error = "This puzzle is not self-consistent";
1491 else
1492 *error = "Unable to find a unique solution for this puzzle";
1493 return NULL;
1494 }
1495 free_soln = true;
1496 }
1497
1498 /*
1499 * Construct a move string which turns the current state into
1500 * the solved state.
1501 */
1502 movesize = 256;
1503 move = snewn(movesize, char);
1504 movelen = 0;
1505 move[movelen++] = 'S';
1506 move[movelen] = '\0';
1507 for (y = 0; y < h; y++)
1508 for (x = 0; x < w; x++) {
1509 int v = (soln[y*w+x] == bs ? -1 : +1);
1510 if (state->soln[y*w+x] != v) {
1511 int len = sprintf(buf, ";%c%d,%d", (int)(v < 0 ? '\\' : '/'), x, y);
1512 if (movelen + len >= movesize) {
1513 movesize = movelen + len + 256;
1514 move = sresize(move, movesize, char);
1515 }
1516 strcpy(move + movelen, buf);
1517 movelen += len;
1518 }
1519 }
1520
1521 if (free_soln)
1522 sfree(soln);
1523
1524 return move;
1525 }
1526
game_can_format_as_text_now(const game_params * params)1527 static bool game_can_format_as_text_now(const game_params *params)
1528 {
1529 return true;
1530 }
1531
game_text_format(const game_state * state)1532 static char *game_text_format(const game_state *state)
1533 {
1534 int w = state->p.w, h = state->p.h, W = w+1, H = h+1;
1535 int x, y, len;
1536 char *ret, *p;
1537
1538 /*
1539 * There are h+H rows of w+W columns.
1540 */
1541 len = (h+H) * (w+W+1) + 1;
1542 ret = snewn(len, char);
1543 p = ret;
1544
1545 for (y = 0; y < H; y++) {
1546 for (x = 0; x < W; x++) {
1547 if (state->clues->clues[y*W+x] >= 0)
1548 *p++ = state->clues->clues[y*W+x] + '0';
1549 else
1550 *p++ = '+';
1551 if (x < w)
1552 *p++ = '-';
1553 }
1554 *p++ = '\n';
1555 if (y < h) {
1556 for (x = 0; x < W; x++) {
1557 *p++ = '|';
1558 if (x < w) {
1559 if (state->soln[y*w+x] != 0)
1560 *p++ = (state->soln[y*w+x] < 0 ? '\\' : '/');
1561 else
1562 *p++ = ' ';
1563 }
1564 }
1565 *p++ = '\n';
1566 }
1567 }
1568 *p++ = '\0';
1569
1570 assert(p - ret == len);
1571 return ret;
1572 }
1573
1574 struct game_ui {
1575 int cur_x, cur_y;
1576 bool cur_visible;
1577 };
1578
new_ui(const game_state * state)1579 static game_ui *new_ui(const game_state *state)
1580 {
1581 game_ui *ui = snew(game_ui);
1582 ui->cur_x = ui->cur_y = 0;
1583 ui->cur_visible = false;
1584 return ui;
1585 }
1586
free_ui(game_ui * ui)1587 static void free_ui(game_ui *ui)
1588 {
1589 sfree(ui);
1590 }
1591
encode_ui(const game_ui * ui)1592 static char *encode_ui(const game_ui *ui)
1593 {
1594 return NULL;
1595 }
1596
decode_ui(game_ui * ui,const char * encoding)1597 static void decode_ui(game_ui *ui, const char *encoding)
1598 {
1599 }
1600
game_changed_state(game_ui * ui,const game_state * oldstate,const game_state * newstate)1601 static void game_changed_state(game_ui *ui, const game_state *oldstate,
1602 const game_state *newstate)
1603 {
1604 }
1605
1606 #define PREFERRED_TILESIZE 32
1607 #define TILESIZE (ds->tilesize)
1608 #define BORDER TILESIZE
1609 #define CLUE_RADIUS (TILESIZE / 3)
1610 #define CLUE_TEXTSIZE (TILESIZE / 2)
1611 #define COORD(x) ( (x) * TILESIZE + BORDER )
1612 #define FROMCOORD(x) ( ((x) - BORDER + TILESIZE) / TILESIZE - 1 )
1613
1614 #define FLASH_TIME 0.30F
1615
1616 /*
1617 * Bit fields in the `grid' and `todraw' elements of the drawstate.
1618 */
1619 #define BACKSLASH 0x00000001L
1620 #define FORWSLASH 0x00000002L
1621 #define L_T 0x00000004L
1622 #define ERR_L_T 0x00000008L
1623 #define L_B 0x00000010L
1624 #define ERR_L_B 0x00000020L
1625 #define T_L 0x00000040L
1626 #define ERR_T_L 0x00000080L
1627 #define T_R 0x00000100L
1628 #define ERR_T_R 0x00000200L
1629 #define C_TL 0x00000400L
1630 #define ERR_C_TL 0x00000800L
1631 #define FLASH 0x00001000L
1632 #define ERRSLASH 0x00002000L
1633 #define ERR_TL 0x00004000L
1634 #define ERR_TR 0x00008000L
1635 #define ERR_BL 0x00010000L
1636 #define ERR_BR 0x00020000L
1637 #define CURSOR 0x00040000L
1638
1639 struct game_drawstate {
1640 int tilesize;
1641 long *grid;
1642 long *todraw;
1643 };
1644
interpret_move(const game_state * state,game_ui * ui,const game_drawstate * ds,int x,int y,int button)1645 static char *interpret_move(const game_state *state, game_ui *ui,
1646 const game_drawstate *ds,
1647 int x, int y, int button)
1648 {
1649 int w = state->p.w, h = state->p.h;
1650 int v;
1651 char buf[80];
1652 enum { CLOCKWISE, ANTICLOCKWISE, NONE } action = NONE;
1653
1654 if (button == LEFT_BUTTON || button == RIGHT_BUTTON) {
1655 /*
1656 * This is an utterly awful hack which I should really sort out
1657 * by means of a proper configuration mechanism. One Slant
1658 * player has observed that they prefer the mouse buttons to
1659 * function exactly the opposite way round, so here's a
1660 * mechanism for environment-based configuration. I cache the
1661 * result in a global variable - yuck! - to avoid repeated
1662 * lookups.
1663 */
1664 {
1665 static int swap_buttons = -1;
1666 if (swap_buttons < 0) {
1667 char *env = getenv("SLANT_SWAP_BUTTONS");
1668 swap_buttons = (env && (env[0] == 'y' || env[0] == 'Y'));
1669 }
1670 if (swap_buttons) {
1671 if (button == LEFT_BUTTON)
1672 button = RIGHT_BUTTON;
1673 else
1674 button = LEFT_BUTTON;
1675 }
1676 }
1677 action = (button == LEFT_BUTTON) ? CLOCKWISE : ANTICLOCKWISE;
1678
1679 x = FROMCOORD(x);
1680 y = FROMCOORD(y);
1681 if (x < 0 || y < 0 || x >= w || y >= h)
1682 return NULL;
1683 ui->cur_visible = false;
1684 } else if (IS_CURSOR_SELECT(button)) {
1685 if (!ui->cur_visible) {
1686 ui->cur_visible = true;
1687 return UI_UPDATE;
1688 }
1689 x = ui->cur_x;
1690 y = ui->cur_y;
1691
1692 action = (button == CURSOR_SELECT2) ? ANTICLOCKWISE : CLOCKWISE;
1693 } else if (IS_CURSOR_MOVE(button)) {
1694 move_cursor(button, &ui->cur_x, &ui->cur_y, w, h, false);
1695 ui->cur_visible = true;
1696 return UI_UPDATE;
1697 } else if (button == '\\' || button == '\b' || button == '/') {
1698 int x = ui->cur_x, y = ui->cur_y;
1699 if (button == ("\\" "\b" "/")[state->soln[y*w + x] + 1]) return NULL;
1700 sprintf(buf, "%c%d,%d", button == '\b' ? 'C' : button, x, y);
1701 return dupstr(buf);
1702 }
1703
1704 if (action != NONE) {
1705 if (action == CLOCKWISE) {
1706 /*
1707 * Left-clicking cycles blank -> \ -> / -> blank.
1708 */
1709 v = state->soln[y*w+x] - 1;
1710 if (v == -2)
1711 v = +1;
1712 } else {
1713 /*
1714 * Right-clicking cycles blank -> / -> \ -> blank.
1715 */
1716 v = state->soln[y*w+x] + 1;
1717 if (v == +2)
1718 v = -1;
1719 }
1720
1721 sprintf(buf, "%c%d,%d", (int)(v==-1 ? '\\' : v==+1 ? '/' : 'C'), x, y);
1722 return dupstr(buf);
1723 }
1724
1725 return NULL;
1726 }
1727
execute_move(const game_state * state,const char * move)1728 static game_state *execute_move(const game_state *state, const char *move)
1729 {
1730 int w = state->p.w, h = state->p.h;
1731 char c;
1732 int x, y, n;
1733 game_state *ret = dup_game(state);
1734
1735 while (*move) {
1736 c = *move;
1737 if (c == 'S') {
1738 ret->used_solve = true;
1739 move++;
1740 } else if (c == '\\' || c == '/' || c == 'C') {
1741 move++;
1742 if (sscanf(move, "%d,%d%n", &x, &y, &n) != 2 ||
1743 x < 0 || y < 0 || x >= w || y >= h) {
1744 free_game(ret);
1745 return NULL;
1746 }
1747 ret->soln[y*w+x] = (c == '\\' ? -1 : c == '/' ? +1 : 0);
1748 move += n;
1749 } else {
1750 free_game(ret);
1751 return NULL;
1752 }
1753 if (*move == ';')
1754 move++;
1755 else if (*move) {
1756 free_game(ret);
1757 return NULL;
1758 }
1759 }
1760
1761 /*
1762 * We never clear the `completed' flag, but we must always
1763 * re-run the completion check because it also highlights
1764 * errors in the grid.
1765 */
1766 ret->completed = check_completion(ret) || ret->completed;
1767
1768 return ret;
1769 }
1770
1771 /* ----------------------------------------------------------------------
1772 * Drawing routines.
1773 */
1774
game_compute_size(const game_params * params,int tilesize,int * x,int * y)1775 static void game_compute_size(const game_params *params, int tilesize,
1776 int *x, int *y)
1777 {
1778 /* fool the macros */
1779 struct dummy { int tilesize; } dummy, *ds = &dummy;
1780 dummy.tilesize = tilesize;
1781
1782 *x = 2 * BORDER + params->w * TILESIZE + 1;
1783 *y = 2 * BORDER + params->h * TILESIZE + 1;
1784 }
1785
game_set_size(drawing * dr,game_drawstate * ds,const game_params * params,int tilesize)1786 static void game_set_size(drawing *dr, game_drawstate *ds,
1787 const game_params *params, int tilesize)
1788 {
1789 ds->tilesize = tilesize;
1790 }
1791
game_colours(frontend * fe,int * ncolours)1792 static float *game_colours(frontend *fe, int *ncolours)
1793 {
1794 float *ret = snewn(3 * NCOLOURS, float);
1795
1796 /* CURSOR colour is a background highlight. */
1797 game_mkhighlight(fe, ret, COL_BACKGROUND, COL_CURSOR, -1);
1798
1799 ret[COL_FILLEDSQUARE * 3 + 0] = ret[COL_BACKGROUND * 3 + 0];
1800 ret[COL_FILLEDSQUARE * 3 + 1] = ret[COL_BACKGROUND * 3 + 1];
1801 ret[COL_FILLEDSQUARE * 3 + 2] = ret[COL_BACKGROUND * 3 + 2];
1802
1803 ret[COL_GRID * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 0.7F;
1804 ret[COL_GRID * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 0.7F;
1805 ret[COL_GRID * 3 + 2] = ret[COL_BACKGROUND * 3 + 2] * 0.7F;
1806
1807 ret[COL_INK * 3 + 0] = 0.0F;
1808 ret[COL_INK * 3 + 1] = 0.0F;
1809 ret[COL_INK * 3 + 2] = 0.0F;
1810
1811 ret[COL_SLANT1 * 3 + 0] = 0.0F;
1812 ret[COL_SLANT1 * 3 + 1] = 0.0F;
1813 ret[COL_SLANT1 * 3 + 2] = 0.0F;
1814
1815 ret[COL_SLANT2 * 3 + 0] = 0.0F;
1816 ret[COL_SLANT2 * 3 + 1] = 0.0F;
1817 ret[COL_SLANT2 * 3 + 2] = 0.0F;
1818
1819 ret[COL_ERROR * 3 + 0] = 1.0F;
1820 ret[COL_ERROR * 3 + 1] = 0.0F;
1821 ret[COL_ERROR * 3 + 2] = 0.0F;
1822
1823 *ncolours = NCOLOURS;
1824 return ret;
1825 }
1826
game_new_drawstate(drawing * dr,const game_state * state)1827 static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
1828 {
1829 int w = state->p.w, h = state->p.h;
1830 int i;
1831 struct game_drawstate *ds = snew(struct game_drawstate);
1832
1833 ds->tilesize = 0;
1834 ds->grid = snewn((w+2)*(h+2), long);
1835 ds->todraw = snewn((w+2)*(h+2), long);
1836 for (i = 0; i < (w+2)*(h+2); i++)
1837 ds->grid[i] = ds->todraw[i] = -1;
1838
1839 return ds;
1840 }
1841
game_free_drawstate(drawing * dr,game_drawstate * ds)1842 static void game_free_drawstate(drawing *dr, game_drawstate *ds)
1843 {
1844 sfree(ds->todraw);
1845 sfree(ds->grid);
1846 sfree(ds);
1847 }
1848
draw_clue(drawing * dr,game_drawstate * ds,int x,int y,long v,bool err,int bg,int colour)1849 static void draw_clue(drawing *dr, game_drawstate *ds,
1850 int x, int y, long v, bool err, int bg, int colour)
1851 {
1852 char p[2];
1853 int ccol = colour >= 0 ? colour : ((x ^ y) & 1) ? COL_SLANT1 : COL_SLANT2;
1854 int tcol = colour >= 0 ? colour : err ? COL_ERROR : COL_INK;
1855
1856 if (v < 0)
1857 return;
1858
1859 p[0] = (char)v + '0';
1860 p[1] = '\0';
1861 draw_circle(dr, COORD(x), COORD(y), CLUE_RADIUS,
1862 bg >= 0 ? bg : COL_BACKGROUND, ccol);
1863 draw_text(dr, COORD(x), COORD(y), FONT_VARIABLE,
1864 CLUE_TEXTSIZE, ALIGN_VCENTRE|ALIGN_HCENTRE, tcol, p);
1865 }
1866
draw_tile(drawing * dr,game_drawstate * ds,game_clues * clues,int x,int y,long v)1867 static void draw_tile(drawing *dr, game_drawstate *ds, game_clues *clues,
1868 int x, int y, long v)
1869 {
1870 int w = clues->w, h = clues->h, W = w+1 /*, H = h+1 */;
1871 int chesscolour = (x ^ y) & 1;
1872 int fscol = chesscolour ? COL_SLANT2 : COL_SLANT1;
1873 int bscol = chesscolour ? COL_SLANT1 : COL_SLANT2;
1874
1875 clip(dr, COORD(x), COORD(y), TILESIZE, TILESIZE);
1876
1877 draw_rect(dr, COORD(x), COORD(y), TILESIZE, TILESIZE,
1878 (v & FLASH) ? COL_GRID :
1879 (v & CURSOR) ? COL_CURSOR :
1880 (v & (BACKSLASH | FORWSLASH)) ? COL_FILLEDSQUARE :
1881 COL_BACKGROUND);
1882
1883 /*
1884 * Draw the grid lines.
1885 */
1886 if (x >= 0 && x < w && y >= 0)
1887 draw_rect(dr, COORD(x), COORD(y), TILESIZE+1, 1, COL_GRID);
1888 if (x >= 0 && x < w && y < h)
1889 draw_rect(dr, COORD(x), COORD(y+1), TILESIZE+1, 1, COL_GRID);
1890 if (y >= 0 && y < h && x >= 0)
1891 draw_rect(dr, COORD(x), COORD(y), 1, TILESIZE+1, COL_GRID);
1892 if (y >= 0 && y < h && x < w)
1893 draw_rect(dr, COORD(x+1), COORD(y), 1, TILESIZE+1, COL_GRID);
1894 if (x == -1 && y == -1)
1895 draw_rect(dr, COORD(x+1), COORD(y+1), 1, 1, COL_GRID);
1896 if (x == -1 && y == h)
1897 draw_rect(dr, COORD(x+1), COORD(y), 1, 1, COL_GRID);
1898 if (x == w && y == -1)
1899 draw_rect(dr, COORD(x), COORD(y+1), 1, 1, COL_GRID);
1900 if (x == w && y == h)
1901 draw_rect(dr, COORD(x), COORD(y), 1, 1, COL_GRID);
1902
1903 /*
1904 * Draw the slash.
1905 */
1906 if (v & BACKSLASH) {
1907 int scol = (v & ERRSLASH) ? COL_ERROR : bscol;
1908 draw_line(dr, COORD(x), COORD(y), COORD(x+1), COORD(y+1), scol);
1909 draw_line(dr, COORD(x)+1, COORD(y), COORD(x+1), COORD(y+1)-1,
1910 scol);
1911 draw_line(dr, COORD(x), COORD(y)+1, COORD(x+1)-1, COORD(y+1),
1912 scol);
1913 } else if (v & FORWSLASH) {
1914 int scol = (v & ERRSLASH) ? COL_ERROR : fscol;
1915 draw_line(dr, COORD(x+1), COORD(y), COORD(x), COORD(y+1), scol);
1916 draw_line(dr, COORD(x+1)-1, COORD(y), COORD(x), COORD(y+1)-1,
1917 scol);
1918 draw_line(dr, COORD(x+1), COORD(y)+1, COORD(x)+1, COORD(y+1),
1919 scol);
1920 }
1921
1922 /*
1923 * Draw dots on the grid corners that appear if a slash is in a
1924 * neighbouring cell.
1925 */
1926 if (v & (L_T | BACKSLASH))
1927 draw_rect(dr, COORD(x), COORD(y)+1, 1, 1,
1928 (v & ERR_L_T ? COL_ERROR : bscol));
1929 if (v & (L_B | FORWSLASH))
1930 draw_rect(dr, COORD(x), COORD(y+1)-1, 1, 1,
1931 (v & ERR_L_B ? COL_ERROR : fscol));
1932 if (v & (T_L | BACKSLASH))
1933 draw_rect(dr, COORD(x)+1, COORD(y), 1, 1,
1934 (v & ERR_T_L ? COL_ERROR : bscol));
1935 if (v & (T_R | FORWSLASH))
1936 draw_rect(dr, COORD(x+1)-1, COORD(y), 1, 1,
1937 (v & ERR_T_R ? COL_ERROR : fscol));
1938 if (v & (C_TL | BACKSLASH))
1939 draw_rect(dr, COORD(x), COORD(y), 1, 1,
1940 (v & ERR_C_TL ? COL_ERROR : bscol));
1941
1942 /*
1943 * And finally the clues at the corners.
1944 */
1945 if (x >= 0 && y >= 0)
1946 draw_clue(dr, ds, x, y, clues->clues[y*W+x], v & ERR_TL, -1, -1);
1947 if (x < w && y >= 0)
1948 draw_clue(dr, ds, x+1, y, clues->clues[y*W+(x+1)], v & ERR_TR, -1, -1);
1949 if (x >= 0 && y < h)
1950 draw_clue(dr, ds, x, y+1, clues->clues[(y+1)*W+x], v & ERR_BL, -1, -1);
1951 if (x < w && y < h)
1952 draw_clue(dr, ds, x+1, y+1, clues->clues[(y+1)*W+(x+1)], v & ERR_BR,
1953 -1, -1);
1954
1955 unclip(dr);
1956 draw_update(dr, COORD(x), COORD(y), TILESIZE, TILESIZE);
1957 }
1958
game_redraw(drawing * dr,game_drawstate * ds,const game_state * oldstate,const game_state * state,int dir,const game_ui * ui,float animtime,float flashtime)1959 static void game_redraw(drawing *dr, game_drawstate *ds,
1960 const game_state *oldstate, const game_state *state,
1961 int dir, const game_ui *ui,
1962 float animtime, float flashtime)
1963 {
1964 int w = state->p.w, h = state->p.h, W = w+1, H = h+1;
1965 int x, y;
1966 bool flashing;
1967
1968 if (flashtime > 0)
1969 flashing = (int)(flashtime * 3 / FLASH_TIME) != 1;
1970 else
1971 flashing = false;
1972
1973 /*
1974 * Loop over the grid and work out where all the slashes are.
1975 * We need to do this because a slash in one square affects the
1976 * drawing of the next one along.
1977 */
1978 for (y = -1; y <= h; y++)
1979 for (x = -1; x <= w; x++) {
1980 if (x >= 0 && x < w && y >= 0 && y < h)
1981 ds->todraw[(y+1)*(w+2)+(x+1)] = flashing ? FLASH : 0;
1982 else
1983 ds->todraw[(y+1)*(w+2)+(x+1)] = 0;
1984 }
1985
1986 for (y = 0; y < h; y++) {
1987 for (x = 0; x < w; x++) {
1988 bool err = state->errors[y*W+x] & ERR_SQUARE;
1989
1990 if (state->soln[y*w+x] < 0) {
1991 ds->todraw[(y+1)*(w+2)+(x+1)] |= BACKSLASH;
1992 ds->todraw[(y+2)*(w+2)+(x+1)] |= T_R;
1993 ds->todraw[(y+1)*(w+2)+(x+2)] |= L_B;
1994 ds->todraw[(y+2)*(w+2)+(x+2)] |= C_TL;
1995 if (err) {
1996 ds->todraw[(y+1)*(w+2)+(x+1)] |= ERRSLASH |
1997 ERR_T_L | ERR_L_T | ERR_C_TL;
1998 ds->todraw[(y+2)*(w+2)+(x+1)] |= ERR_T_R;
1999 ds->todraw[(y+1)*(w+2)+(x+2)] |= ERR_L_B;
2000 ds->todraw[(y+2)*(w+2)+(x+2)] |= ERR_C_TL;
2001 }
2002 } else if (state->soln[y*w+x] > 0) {
2003 ds->todraw[(y+1)*(w+2)+(x+1)] |= FORWSLASH;
2004 ds->todraw[(y+1)*(w+2)+(x+2)] |= L_T | C_TL;
2005 ds->todraw[(y+2)*(w+2)+(x+1)] |= T_L | C_TL;
2006 if (err) {
2007 ds->todraw[(y+1)*(w+2)+(x+1)] |= ERRSLASH |
2008 ERR_L_B | ERR_T_R;
2009 ds->todraw[(y+1)*(w+2)+(x+2)] |= ERR_L_T | ERR_C_TL;
2010 ds->todraw[(y+2)*(w+2)+(x+1)] |= ERR_T_L | ERR_C_TL;
2011 }
2012 }
2013 if (ui->cur_visible && ui->cur_x == x && ui->cur_y == y)
2014 ds->todraw[(y+1)*(w+2)+(x+1)] |= CURSOR;
2015 }
2016 }
2017
2018 for (y = 0; y < H; y++)
2019 for (x = 0; x < W; x++)
2020 if (state->errors[y*W+x] & ERR_VERTEX) {
2021 ds->todraw[y*(w+2)+x] |= ERR_BR;
2022 ds->todraw[y*(w+2)+(x+1)] |= ERR_BL;
2023 ds->todraw[(y+1)*(w+2)+x] |= ERR_TR;
2024 ds->todraw[(y+1)*(w+2)+(x+1)] |= ERR_TL;
2025 }
2026
2027 /*
2028 * Now go through and draw the grid squares.
2029 */
2030 for (y = -1; y <= h; y++) {
2031 for (x = -1; x <= w; x++) {
2032 if (ds->todraw[(y+1)*(w+2)+(x+1)] != ds->grid[(y+1)*(w+2)+(x+1)]) {
2033 draw_tile(dr, ds, state->clues, x, y,
2034 ds->todraw[(y+1)*(w+2)+(x+1)]);
2035 ds->grid[(y+1)*(w+2)+(x+1)] = ds->todraw[(y+1)*(w+2)+(x+1)];
2036 }
2037 }
2038 }
2039 }
2040
game_anim_length(const game_state * oldstate,const game_state * newstate,int dir,game_ui * ui)2041 static float game_anim_length(const game_state *oldstate,
2042 const game_state *newstate, int dir, game_ui *ui)
2043 {
2044 return 0.0F;
2045 }
2046
game_flash_length(const game_state * oldstate,const game_state * newstate,int dir,game_ui * ui)2047 static float game_flash_length(const game_state *oldstate,
2048 const game_state *newstate, int dir, game_ui *ui)
2049 {
2050 if (!oldstate->completed && newstate->completed &&
2051 !oldstate->used_solve && !newstate->used_solve)
2052 return FLASH_TIME;
2053
2054 return 0.0F;
2055 }
2056
game_get_cursor_location(const game_ui * ui,const game_drawstate * ds,const game_state * state,const game_params * params,int * x,int * y,int * w,int * h)2057 static void game_get_cursor_location(const game_ui *ui,
2058 const game_drawstate *ds,
2059 const game_state *state,
2060 const game_params *params,
2061 int *x, int *y, int *w, int *h)
2062 {
2063 if(ui->cur_visible) {
2064 *x = COORD(ui->cur_x);
2065 *y = COORD(ui->cur_y);
2066 *w = *h = TILESIZE;
2067 }
2068 }
2069
game_status(const game_state * state)2070 static int game_status(const game_state *state)
2071 {
2072 return state->completed ? +1 : 0;
2073 }
2074
game_timing_state(const game_state * state,game_ui * ui)2075 static bool game_timing_state(const game_state *state, game_ui *ui)
2076 {
2077 return true;
2078 }
2079
game_print_size(const game_params * params,float * x,float * y)2080 static void game_print_size(const game_params *params, float *x, float *y)
2081 {
2082 int pw, ph;
2083
2084 /*
2085 * I'll use 6mm squares by default.
2086 */
2087 game_compute_size(params, 600, &pw, &ph);
2088 *x = pw / 100.0F;
2089 *y = ph / 100.0F;
2090 }
2091
game_print(drawing * dr,const game_state * state,int tilesize)2092 static void game_print(drawing *dr, const game_state *state, int tilesize)
2093 {
2094 int w = state->p.w, h = state->p.h, W = w+1;
2095 int ink = print_mono_colour(dr, 0);
2096 int paper = print_mono_colour(dr, 1);
2097 int x, y;
2098
2099 /* Ick: fake up `ds->tilesize' for macro expansion purposes */
2100 game_drawstate ads, *ds = &ads;
2101 game_set_size(dr, ds, NULL, tilesize);
2102
2103 /*
2104 * Border.
2105 */
2106 print_line_width(dr, TILESIZE / 16);
2107 draw_rect_outline(dr, COORD(0), COORD(0), w*TILESIZE, h*TILESIZE, ink);
2108
2109 /*
2110 * Grid.
2111 */
2112 print_line_width(dr, TILESIZE / 24);
2113 for (x = 1; x < w; x++)
2114 draw_line(dr, COORD(x), COORD(0), COORD(x), COORD(h), ink);
2115 for (y = 1; y < h; y++)
2116 draw_line(dr, COORD(0), COORD(y), COORD(w), COORD(y), ink);
2117
2118 /*
2119 * Solution.
2120 */
2121 print_line_width(dr, TILESIZE / 12);
2122 for (y = 0; y < h; y++)
2123 for (x = 0; x < w; x++)
2124 if (state->soln[y*w+x]) {
2125 int ly, ry;
2126 /*
2127 * To prevent nasty line-ending artefacts at
2128 * corners, I'll do something slightly cunning
2129 * here.
2130 */
2131 clip(dr, COORD(x), COORD(y), TILESIZE, TILESIZE);
2132 if (state->soln[y*w+x] < 0)
2133 ly = y-1, ry = y+2;
2134 else
2135 ry = y-1, ly = y+2;
2136 draw_line(dr, COORD(x-1), COORD(ly), COORD(x+2), COORD(ry),
2137 ink);
2138 unclip(dr);
2139 }
2140
2141 /*
2142 * Clues.
2143 */
2144 print_line_width(dr, TILESIZE / 24);
2145 for (y = 0; y <= h; y++)
2146 for (x = 0; x <= w; x++)
2147 draw_clue(dr, ds, x, y, state->clues->clues[y*W+x],
2148 false, paper, ink);
2149 }
2150
2151 #ifdef COMBINED
2152 #define thegame slant
2153 #endif
2154
2155 const struct game thegame = {
2156 "Slant", "games.slant", "slant",
2157 default_params,
2158 game_fetch_preset, NULL,
2159 decode_params,
2160 encode_params,
2161 free_params,
2162 dup_params,
2163 true, game_configure, custom_params,
2164 validate_params,
2165 new_game_desc,
2166 validate_desc,
2167 new_game,
2168 dup_game,
2169 free_game,
2170 true, solve_game,
2171 true, game_can_format_as_text_now, game_text_format,
2172 new_ui,
2173 free_ui,
2174 encode_ui,
2175 decode_ui,
2176 NULL, /* game_request_keys */
2177 game_changed_state,
2178 interpret_move,
2179 execute_move,
2180 PREFERRED_TILESIZE, game_compute_size, game_set_size,
2181 game_colours,
2182 game_new_drawstate,
2183 game_free_drawstate,
2184 game_redraw,
2185 game_anim_length,
2186 game_flash_length,
2187 game_get_cursor_location,
2188 game_status,
2189 true, false, game_print_size, game_print,
2190 false, /* wants_statusbar */
2191 false, game_timing_state,
2192 0, /* flags */
2193 };
2194
2195 #ifdef STANDALONE_SOLVER
2196
2197 #include <stdarg.h>
2198
main(int argc,char ** argv)2199 int main(int argc, char **argv)
2200 {
2201 game_params *p;
2202 game_state *s;
2203 char *id = NULL, *desc;
2204 const char *err;
2205 bool grade = false;
2206 int ret, diff;
2207 bool really_verbose = false;
2208 struct solver_scratch *sc;
2209
2210 while (--argc > 0) {
2211 char *p = *++argv;
2212 if (!strcmp(p, "-v")) {
2213 really_verbose = true;
2214 } else if (!strcmp(p, "-g")) {
2215 grade = true;
2216 } else if (*p == '-') {
2217 fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0], p);
2218 return 1;
2219 } else {
2220 id = p;
2221 }
2222 }
2223
2224 if (!id) {
2225 fprintf(stderr, "usage: %s [-g | -v] <game_id>\n", argv[0]);
2226 return 1;
2227 }
2228
2229 desc = strchr(id, ':');
2230 if (!desc) {
2231 fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]);
2232 return 1;
2233 }
2234 *desc++ = '\0';
2235
2236 p = default_params();
2237 decode_params(p, id);
2238 err = validate_desc(p, desc);
2239 if (err) {
2240 fprintf(stderr, "%s: %s\n", argv[0], err);
2241 return 1;
2242 }
2243 s = new_game(NULL, p, desc);
2244
2245 sc = new_scratch(p->w, p->h);
2246
2247 /*
2248 * When solving an Easy puzzle, we don't want to bother the
2249 * user with Hard-level deductions. For this reason, we grade
2250 * the puzzle internally before doing anything else.
2251 */
2252 ret = -1; /* placate optimiser */
2253 for (diff = 0; diff < DIFFCOUNT; diff++) {
2254 ret = slant_solve(p->w, p->h, s->clues->clues,
2255 s->soln, sc, diff);
2256 if (ret < 2)
2257 break;
2258 }
2259
2260 if (diff == DIFFCOUNT) {
2261 if (grade)
2262 printf("Difficulty rating: harder than Hard, or ambiguous\n");
2263 else
2264 printf("Unable to find a unique solution\n");
2265 } else {
2266 if (grade) {
2267 if (ret == 0)
2268 printf("Difficulty rating: impossible (no solution exists)\n");
2269 else if (ret == 1)
2270 printf("Difficulty rating: %s\n", slant_diffnames[diff]);
2271 } else {
2272 verbose = really_verbose;
2273 ret = slant_solve(p->w, p->h, s->clues->clues,
2274 s->soln, sc, diff);
2275 if (ret == 0)
2276 printf("Puzzle is inconsistent\n");
2277 else
2278 fputs(game_text_format(s), stdout);
2279 }
2280 }
2281
2282 return 0;
2283 }
2284
2285 #endif
2286
2287 /* vim: set shiftwidth=4 tabstop=8: */
2288