11d273f7 |
1 | /* |
2 | * Library code to divide up a rectangle into a number of equally |
3 | * sized ominoes, in a random fashion. |
4 | * |
5 | * Could use this for generating solved grids of |
6 | * http://www.nikoli.co.jp/ja/puzzles/block_puzzle/ |
7 | * or for generating the playfield for Jigsaw Sudoku. |
8 | */ |
9 | |
9d36cbd7 |
10 | /* |
82ed4789 |
11 | * This code is restricted to simply connected solutions: that is, |
12 | * no single polyomino may completely surround another (not even |
13 | * with a corner visible to the outside world, in the sense that a |
14 | * 7-omino can `surround' a single square). |
15 | * |
16 | * It's tempting to think that this is a natural consequence of |
17 | * all the ominoes being the same size - after all, a division of |
18 | * anything into 7-ominoes must necessarily have all of them |
19 | * simply connected, because if one was not then the 1-square |
20 | * space in the middle could not be part of any 7-omino - but in |
21 | * fact, for sufficiently large k, it is perfectly possible for a |
22 | * k-omino to completely surround another k-omino. A simple |
23 | * example is this one with two 25-ominoes: |
24 | * |
25 | * +--+--+--+--+--+--+--+ |
26 | * | | |
27 | * + +--+--+--+--+--+ + |
28 | * | | | | |
29 | * + + + + |
30 | * | | | | |
31 | * + + + +--+ |
32 | * | | | | |
33 | * + + + +--+ |
34 | * | | | | |
35 | * + + + + |
36 | * | | | | |
37 | * + +--+--+--+--+--+ + |
38 | * | | |
39 | * +--+--+--+--+--+--+--+ |
40 | * |
41 | * I believe the smallest k which can manage this is 23, which I |
42 | * derive by considering the largest _rectangle_ a k-omino can |
43 | * surround. Consider: to surround an m x n rectangle, a polyomino |
44 | * must have 2m squares along the two m-sides of the rectangle, 2n |
45 | * squares along the n-sides, and fill in three of the corners. So |
46 | * m+n must be at most (k-3)/2. Hence, to find the largest area of |
47 | * such a rectangle, we must find m so as to maximise the product |
48 | * m((k-3)/2-m). This is achieved when m is as close as possible |
49 | * to half of (k-3)/2; so the largest rectangle surroundable by a |
50 | * k-omino is equal to floor(k'/2)*ceil(k'/2), with k'=(k-3)/2. |
51 | * The smallest k for which this is at least k is 23: a 23-omino |
52 | * can surround a 5x5 rectangle, whereas the best a 22-omino can |
53 | * manage is a 5x4. |
54 | * |
55 | * (I don't have a definite argument to show that a k-omino cannot |
56 | * surround a larger area in non-rectangular than rectangular |
57 | * form, but it seems intuitively obvious to me that it can't. I |
58 | * may update this with a more rigorous proof if I think of one.) |
59 | * |
60 | * Anyway: the point is, although constructions of this type are |
61 | * possible for sufficiently large k, divvy_rectangle() will never |
62 | * generate them. This could be considered a weakness for some |
63 | * purposes, in the sense that we can't generate all possible |
64 | * divisions. However, there are many divisions which we are |
65 | * highly unlikely to generate anyway, so in practice it probably |
66 | * isn't _too_ bad. |
67 | * |
68 | * If I wanted to fix this issue, I would have to make the rules |
69 | * more complicated for determining when a square can safely be |
70 | * _removed_ from a polyomino. Adding one becomes easier (a square |
71 | * may be added to a polyomino iff it is 4-adjacent to any square |
72 | * currently part of the polyomino, and the current test for loop |
73 | * formation may be dispensed with), but to determine which |
74 | * squares may be removed we must now resort to analysis of the |
75 | * overall structure of the polyomino rather than the simple local |
76 | * properties we can currently get away with measuring. |
77 | */ |
78 | |
79 | /* |
9d36cbd7 |
80 | * Possible improvements which might cut the fail rate: |
81 | * |
82 | * - instead of picking one omino to extend in an iteration, try |
83 | * them all in succession (in a randomised order) |
84 | * |
85 | * - (for real rigour) instead of bfsing over ominoes, bfs over |
86 | * the space of possible _removed squares_. That way we aren't |
87 | * limited to randomly choosing a single square to remove from |
88 | * an omino and failing if that particular square doesn't |
89 | * happen to work. |
90 | * |
4d31c526 |
91 | * However, I don't currently think it's necessary to do either of |
92 | * these, because the failure rate is already low enough to be |
93 | * easily tolerable, under all circumstances I've been able to |
94 | * think of. |
9d36cbd7 |
95 | */ |
96 | |
11d273f7 |
97 | #include <assert.h> |
98 | #include <stdio.h> |
99 | #include <stdlib.h> |
100 | #include <stddef.h> |
101 | |
102 | #include "puzzles.h" |
103 | |
104 | /* |
105 | * Subroutine which implements a function used in computing both |
106 | * whether a square can safely be added to an omino, and whether |
107 | * it can safely be removed. |
108 | * |
109 | * We enumerate the eight squares 8-adjacent to this one, in |
110 | * cyclic order. We go round that loop and count the number of |
111 | * times we find a square owned by the target omino next to one |
112 | * not owned by it. We then return success iff that count is 2. |
113 | * |
114 | * When adding a square to an omino, this is precisely the |
115 | * criterion which tells us that adding the square won't leave a |
116 | * hole in the middle of the omino. (There's no explicit |
117 | * requirement in the statement of our problem that the ominoes be |
118 | * simply connected, but we do know they must be all of equal size |
119 | * and so it's clear that we must avoid leaving holes, since a |
120 | * hole would necessarily be smaller than the maximum omino size.) |
121 | * |
122 | * When removing a square from an omino, the _same_ criterion |
123 | * tells us that removing the square won't disconnect the omino. |
124 | */ |
125 | static int addremcommon(int w, int h, int x, int y, int *own, int val) |
126 | { |
127 | int neighbours[8]; |
128 | int dir, count; |
129 | |
130 | for (dir = 0; dir < 8; dir++) { |
131 | int dx = ((dir & 3) == 2 ? 0 : dir > 2 && dir < 6 ? +1 : -1); |
132 | int dy = ((dir & 3) == 0 ? 0 : dir < 4 ? -1 : +1); |
133 | int sx = x+dx, sy = y+dy; |
134 | |
135 | if (sx < 0 || sx >= w || sy < 0 || sy >= h) |
136 | neighbours[dir] = -1; /* outside the grid */ |
137 | else |
138 | neighbours[dir] = own[sy*w+sx]; |
139 | } |
140 | |
141 | /* |
142 | * To begin with, check 4-adjacency. |
143 | */ |
144 | if (neighbours[0] != val && neighbours[2] != val && |
145 | neighbours[4] != val && neighbours[6] != val) |
146 | return FALSE; |
147 | |
148 | count = 0; |
149 | |
150 | for (dir = 0; dir < 8; dir++) { |
151 | int next = (dir + 1) & 7; |
152 | int gotthis = (neighbours[dir] == val); |
153 | int gotnext = (neighbours[next] == val); |
154 | |
155 | if (gotthis != gotnext) |
156 | count++; |
157 | } |
158 | |
159 | return (count == 2); |
160 | } |
161 | |
162 | /* |
163 | * w and h are the dimensions of the rectangle. |
164 | * |
165 | * k is the size of the required ominoes. (So k must divide w*h, |
166 | * of course.) |
167 | * |
168 | * The returned result is a w*h-sized dsf. |
169 | * |
170 | * In both of the above suggested use cases, the user would |
171 | * probably want w==h==k, but that isn't a requirement. |
172 | */ |
9d36cbd7 |
173 | static int *divvy_internal(int w, int h, int k, random_state *rs) |
11d273f7 |
174 | { |
175 | int *order, *queue, *tmp, *own, *sizes, *addable, *removable, *retdsf; |
176 | int wh = w*h; |
177 | int i, j, n, x, y, qhead, qtail; |
178 | |
179 | n = wh / k; |
180 | assert(wh == k*n); |
181 | |
182 | order = snewn(wh, int); |
183 | tmp = snewn(wh, int); |
184 | own = snewn(wh, int); |
185 | sizes = snewn(n, int); |
186 | queue = snewn(n, int); |
187 | addable = snewn(wh*4, int); |
188 | removable = snewn(wh, int); |
189 | |
190 | /* |
191 | * Permute the grid squares into a random order, which will be |
192 | * used for iterating over the grid whenever we need to search |
193 | * for something. This prevents directional bias and arranges |
194 | * for the answer to be non-deterministic. |
195 | */ |
196 | for (i = 0; i < wh; i++) |
197 | order[i] = i; |
198 | shuffle(order, wh, sizeof(*order), rs); |
199 | |
200 | /* |
201 | * Begin by choosing a starting square at random for each |
202 | * omino. |
203 | */ |
204 | for (i = 0; i < wh; i++) { |
205 | own[i] = -1; |
206 | } |
207 | for (i = 0; i < n; i++) { |
208 | own[order[i]] = i; |
209 | sizes[i] = 1; |
210 | } |
211 | |
212 | /* |
213 | * Now repeatedly pick a random omino which isn't already at |
214 | * the target size, and find a way to expand it by one. This |
215 | * may involve stealing a square from another omino, in which |
216 | * case we then re-expand that omino, forming a chain of |
217 | * square-stealing which terminates in an as yet unclaimed |
218 | * square. Hence every successful iteration around this loop |
219 | * causes the number of unclaimed squares to drop by one, and |
220 | * so the process is bounded in duration. |
221 | */ |
222 | while (1) { |
223 | |
224 | #ifdef DIVVY_DIAGNOSTICS |
225 | { |
226 | int x, y; |
227 | printf("Top of loop. Current grid:\n"); |
228 | for (y = 0; y < h; y++) { |
229 | for (x = 0; x < w; x++) |
230 | printf("%3d", own[y*w+x]); |
231 | printf("\n"); |
232 | } |
233 | } |
234 | #endif |
235 | |
236 | /* |
237 | * Go over the grid and figure out which squares can |
238 | * safely be added to, or removed from, each omino. We |
239 | * don't take account of other ominoes in this process, so |
240 | * we will often end up knowing that a square can be |
241 | * poached from one omino by another. |
242 | * |
243 | * For each square, there may be up to four ominoes to |
244 | * which it can be added (those to which it is |
245 | * 4-adjacent). |
246 | */ |
247 | for (y = 0; y < h; y++) { |
248 | for (x = 0; x < w; x++) { |
249 | int yx = y*w+x; |
250 | int curr = own[yx]; |
251 | int dir; |
252 | |
253 | if (curr < 0) { |
9d36cbd7 |
254 | removable[yx] = FALSE; /* can't remove if not owned! */ |
255 | } else if (sizes[curr] == 1) { |
256 | removable[yx] = TRUE; /* can always remove a singleton */ |
11d273f7 |
257 | } else { |
258 | /* |
259 | * See if this square can be removed from its |
260 | * omino without disconnecting it. |
261 | */ |
262 | removable[yx] = addremcommon(w, h, x, y, own, curr); |
263 | } |
264 | |
265 | for (dir = 0; dir < 4; dir++) { |
266 | int dx = (dir == 0 ? -1 : dir == 1 ? +1 : 0); |
267 | int dy = (dir == 2 ? -1 : dir == 3 ? +1 : 0); |
268 | int sx = x + dx, sy = y + dy; |
269 | int syx = sy*w+sx; |
270 | |
271 | addable[yx*4+dir] = -1; |
272 | |
273 | if (sx < 0 || sx >= w || sy < 0 || sy >= h) |
274 | continue; /* no omino here! */ |
275 | if (own[syx] < 0) |
276 | continue; /* also no omino here */ |
277 | if (own[syx] == own[yx]) |
278 | continue; /* we already got one */ |
279 | if (!addremcommon(w, h, x, y, own, own[syx])) |
280 | continue; /* would non-simply connect the omino */ |
281 | |
282 | addable[yx*4+dir] = own[syx]; |
283 | } |
284 | } |
285 | } |
286 | |
287 | for (i = j = 0; i < n; i++) |
288 | if (sizes[i] < k) |
289 | tmp[j++] = i; |
290 | if (j == 0) |
291 | break; /* all ominoes are complete! */ |
292 | j = tmp[random_upto(rs, j)]; |
f40d37bd |
293 | #ifdef DIVVY_DIAGNOSTICS |
294 | printf("Trying to extend %d\n", j); |
295 | #endif |
11d273f7 |
296 | |
297 | /* |
298 | * So we're trying to expand omino j. We breadth-first |
299 | * search out from j across the space of ominoes. |
300 | * |
301 | * For bfs purposes, we use two elements of tmp per omino: |
302 | * tmp[2*i+0] tells us which omino we got to i from, and |
303 | * tmp[2*i+1] numbers the grid square that omino stole |
304 | * from us. |
305 | * |
306 | * This requires that wh (the size of tmp) is at least 2n, |
307 | * i.e. k is at least 2. There would have been nothing to |
308 | * stop a user calling this function with k=1, but if they |
309 | * did then we wouldn't have got to _here_ in the code - |
310 | * we would have noticed above that all ominoes were |
311 | * already at their target sizes, and terminated :-) |
312 | */ |
313 | assert(wh >= 2*n); |
314 | for (i = 0; i < n; i++) |
315 | tmp[2*i] = tmp[2*i+1] = -1; |
316 | qhead = qtail = 0; |
317 | queue[qtail++] = j; |
318 | tmp[2*j] = tmp[2*j+1] = -2; /* special value: `starting point' */ |
319 | |
320 | while (qhead < qtail) { |
321 | int tmpsq; |
322 | |
323 | j = queue[qhead]; |
324 | |
325 | /* |
326 | * We wish to expand omino j. However, we might have |
327 | * got here by omino j having a square stolen from it, |
328 | * so first of all we must temporarily mark that |
329 | * square as not belonging to j, so that our adjacency |
330 | * calculations don't assume j _does_ belong to us. |
331 | */ |
332 | tmpsq = tmp[2*j+1]; |
333 | if (tmpsq >= 0) { |
334 | assert(own[tmpsq] == j); |
9d36cbd7 |
335 | own[tmpsq] = -3; |
11d273f7 |
336 | } |
337 | |
338 | /* |
339 | * OK. Now begin by seeing if we can find any |
340 | * unclaimed square into which we can expand omino j. |
341 | * If we find one, the entire bfs terminates. |
342 | */ |
343 | for (i = 0; i < wh; i++) { |
344 | int dir; |
345 | |
9d36cbd7 |
346 | if (own[order[i]] != -1) |
11d273f7 |
347 | continue; /* this square is claimed */ |
9d36cbd7 |
348 | |
349 | /* |
350 | * Special case: if our current omino was size 1 |
351 | * and then had a square stolen from it, it's now |
352 | * size zero, which means it's valid to `expand' |
353 | * it into _any_ unclaimed square. |
354 | */ |
355 | if (sizes[j] == 1 && tmpsq >= 0) |
356 | break; /* got one */ |
357 | |
358 | /* |
359 | * Failing that, we must do the full test for |
360 | * addability. |
361 | */ |
11d273f7 |
362 | for (dir = 0; dir < 4; dir++) |
363 | if (addable[order[i]*4+dir] == j) { |
364 | /* |
365 | * We know this square is addable to this |
366 | * omino with the grid in the state it had |
367 | * at the top of the loop. However, we |
368 | * must now check that it's _still_ |
369 | * addable to this omino when the omino is |
370 | * missing a square. To do this it's only |
371 | * necessary to re-check addremcommon. |
f40d37bd |
372 | */ |
11d273f7 |
373 | if (!addremcommon(w, h, order[i]%w, order[i]/w, |
374 | own, j)) |
375 | continue; |
376 | break; |
377 | } |
378 | if (dir == 4) |
379 | continue; /* we can't add this square to j */ |
9d36cbd7 |
380 | |
11d273f7 |
381 | break; /* got one! */ |
382 | } |
383 | if (i < wh) { |
384 | i = order[i]; |
385 | |
386 | /* |
9d36cbd7 |
387 | * Restore the temporarily removed square _before_ |
388 | * we start shifting ownerships about. |
389 | */ |
390 | if (tmpsq >= 0) |
391 | own[tmpsq] = j; |
392 | |
393 | /* |
11d273f7 |
394 | * We are done. We can add square i to omino j, |
395 | * and then backtrack along the trail in tmp |
396 | * moving squares between ominoes, ending up |
397 | * expanding our starting omino by one. |
398 | */ |
f40d37bd |
399 | #ifdef DIVVY_DIAGNOSTICS |
400 | printf("(%d,%d)", i%w, i/w); |
401 | #endif |
11d273f7 |
402 | while (1) { |
403 | own[i] = j; |
f40d37bd |
404 | #ifdef DIVVY_DIAGNOSTICS |
405 | printf(" -> %d", j); |
406 | #endif |
11d273f7 |
407 | if (tmp[2*j] == -2) |
408 | break; |
409 | i = tmp[2*j+1]; |
410 | j = tmp[2*j]; |
f40d37bd |
411 | #ifdef DIVVY_DIAGNOSTICS |
412 | printf("; (%d,%d)", i%w, i/w); |
413 | #endif |
11d273f7 |
414 | } |
f40d37bd |
415 | #ifdef DIVVY_DIAGNOSTICS |
416 | printf("\n"); |
417 | #endif |
11d273f7 |
418 | |
419 | /* |
420 | * Increment the size of the starting omino. |
421 | */ |
422 | sizes[j]++; |
423 | |
424 | /* |
425 | * Terminate the bfs loop. |
426 | */ |
427 | break; |
428 | } |
429 | |
430 | /* |
431 | * If we get here, we haven't been able to expand |
432 | * omino j into an unclaimed square. So now we begin |
433 | * to investigate expanding it into squares which are |
434 | * claimed by ominoes the bfs has not yet visited. |
435 | */ |
436 | for (i = 0; i < wh; i++) { |
437 | int dir, nj; |
438 | |
439 | nj = own[order[i]]; |
440 | if (nj < 0 || tmp[2*nj] != -1) |
441 | continue; /* unclaimed, or owned by wrong omino */ |
442 | if (!removable[order[i]]) |
443 | continue; /* its omino won't let it go */ |
444 | |
445 | for (dir = 0; dir < 4; dir++) |
446 | if (addable[order[i]*4+dir] == j) { |
447 | /* |
448 | * As above, re-check addremcommon. |
449 | */ |
450 | if (!addremcommon(w, h, order[i]%w, order[i]/w, |
451 | own, j)) |
452 | continue; |
453 | |
454 | /* |
455 | * We have found a square we can use to |
456 | * expand omino j, at the expense of the |
457 | * as-yet unvisited omino nj. So add this |
458 | * to the bfs queue. |
459 | */ |
460 | assert(qtail < n); |
461 | queue[qtail++] = nj; |
462 | tmp[2*nj] = j; |
463 | tmp[2*nj+1] = order[i]; |
464 | |
465 | /* |
466 | * Now terminate the loop over dir, to |
467 | * ensure we don't accidentally add the |
468 | * same omino twice to the queue. |
469 | */ |
470 | break; |
471 | } |
472 | } |
473 | |
474 | /* |
475 | * Restore the temporarily removed square. |
476 | */ |
477 | if (tmpsq >= 0) |
478 | own[tmpsq] = j; |
479 | |
480 | /* |
481 | * Advance the queue head. |
482 | */ |
483 | qhead++; |
484 | } |
485 | |
486 | if (qhead == qtail) { |
487 | /* |
488 | * We have finished the bfs and not found any way to |
489 | * expand omino j. Panic, and return failure. |
490 | * |
491 | * FIXME: or should we loop over all ominoes before we |
492 | * give up? |
493 | */ |
f40d37bd |
494 | #ifdef DIVVY_DIAGNOSTICS |
495 | printf("FAIL!\n"); |
496 | #endif |
11d273f7 |
497 | retdsf = NULL; |
498 | goto cleanup; |
499 | } |
500 | } |
501 | |
f40d37bd |
502 | #ifdef DIVVY_DIAGNOSTICS |
503 | { |
504 | int x, y; |
505 | printf("SUCCESS! Final grid:\n"); |
506 | for (y = 0; y < h; y++) { |
507 | for (x = 0; x < w; x++) |
508 | printf("%3d", own[y*w+x]); |
509 | printf("\n"); |
510 | } |
511 | } |
512 | #endif |
513 | |
11d273f7 |
514 | /* |
515 | * Construct the output dsf. |
516 | */ |
517 | for (i = 0; i < wh; i++) { |
518 | assert(own[i] >= 0 && own[i] < n); |
519 | tmp[own[i]] = i; |
520 | } |
521 | retdsf = snew_dsf(wh); |
522 | for (i = 0; i < wh; i++) { |
523 | dsf_merge(retdsf, i, tmp[own[i]]); |
524 | } |
525 | |
526 | /* |
527 | * Construct the output dsf a different way, to verify that |
528 | * the ominoes really are k-ominoes and we haven't |
529 | * accidentally split one into two disconnected pieces. |
530 | */ |
531 | dsf_init(tmp, wh); |
532 | for (y = 0; y < h; y++) |
533 | for (x = 0; x+1 < w; x++) |
534 | if (own[y*w+x] == own[y*w+(x+1)]) |
535 | dsf_merge(tmp, y*w+x, y*w+(x+1)); |
536 | for (x = 0; x < w; x++) |
537 | for (y = 0; y+1 < h; y++) |
538 | if (own[y*w+x] == own[(y+1)*w+x]) |
539 | dsf_merge(tmp, y*w+x, (y+1)*w+x); |
540 | for (i = 0; i < wh; i++) { |
541 | j = dsf_canonify(retdsf, i); |
542 | assert(dsf_canonify(tmp, j) == dsf_canonify(tmp, i)); |
543 | } |
544 | |
545 | cleanup: |
546 | |
547 | /* |
548 | * Free our temporary working space. |
549 | */ |
550 | sfree(order); |
551 | sfree(tmp); |
552 | sfree(own); |
553 | sfree(sizes); |
554 | sfree(queue); |
555 | sfree(addable); |
556 | sfree(removable); |
557 | |
558 | /* |
559 | * And we're done. |
560 | */ |
561 | return retdsf; |
562 | } |
563 | |
564 | #ifdef TESTMODE |
9d36cbd7 |
565 | static int fail_counter = 0; |
566 | #endif |
567 | |
568 | int *divvy_rectangle(int w, int h, int k, random_state *rs) |
569 | { |
570 | int *ret; |
571 | |
572 | do { |
573 | ret = divvy_internal(w, h, k, rs); |
574 | |
575 | #ifdef TESTMODE |
576 | if (!ret) |
577 | fail_counter++; |
578 | #endif |
579 | |
580 | } while (!ret); |
581 | |
582 | return ret; |
583 | } |
584 | |
585 | #ifdef TESTMODE |
11d273f7 |
586 | |
587 | /* |
588 | * gcc -g -O0 -DTESTMODE -I.. -o divvy divvy.c ../random.c ../malloc.c ../dsf.c ../misc.c ../nullfe.c |
589 | * |
590 | * or to debug |
591 | * |
592 | * gcc -g -O0 -DDIVVY_DIAGNOSTICS -DTESTMODE -I.. -o divvy divvy.c ../random.c ../malloc.c ../dsf.c ../misc.c ../nullfe.c |
593 | */ |
594 | |
595 | int main(int argc, char **argv) |
596 | { |
597 | int *dsf; |
9d36cbd7 |
598 | int i; |
11d273f7 |
599 | int w = 9, h = 4, k = 6, tries = 100; |
600 | random_state *rs; |
601 | |
602 | rs = random_new("123456", 6); |
603 | |
604 | if (argc > 1) |
605 | w = atoi(argv[1]); |
606 | if (argc > 2) |
607 | h = atoi(argv[2]); |
608 | if (argc > 3) |
609 | k = atoi(argv[3]); |
610 | if (argc > 4) |
611 | tries = atoi(argv[4]); |
612 | |
11d273f7 |
613 | for (i = 0; i < tries; i++) { |
9d36cbd7 |
614 | int x, y; |
11d273f7 |
615 | |
9d36cbd7 |
616 | dsf = divvy_rectangle(w, h, k, rs); |
617 | assert(dsf); |
618 | |
619 | for (y = 0; y <= 2*h; y++) { |
620 | for (x = 0; x <= 2*w; x++) { |
621 | int miny = y/2 - 1, maxy = y/2; |
622 | int minx = x/2 - 1, maxx = x/2; |
623 | int classes[4], tx, ty; |
624 | for (ty = 0; ty < 2; ty++) |
625 | for (tx = 0; tx < 2; tx++) { |
626 | int cx = minx+tx, cy = miny+ty; |
627 | if (cx < 0 || cx >= w || cy < 0 || cy >= h) |
628 | classes[ty*2+tx] = -1; |
11d273f7 |
629 | else |
9d36cbd7 |
630 | classes[ty*2+tx] = dsf_canonify(dsf, cy*w+cx); |
11d273f7 |
631 | } |
9d36cbd7 |
632 | switch (y%2 * 2 + x%2) { |
633 | case 0: /* corner */ |
634 | /* |
635 | * Cases for the corner: |
636 | * |
637 | * - if all four surrounding squares belong |
638 | * to the same omino, we print a space. |
639 | * |
640 | * - if the top two are the same and the |
641 | * bottom two are the same, we print a |
642 | * horizontal line. |
643 | * |
644 | * - if the left two are the same and the |
645 | * right two are the same, we print a |
646 | * vertical line. |
647 | * |
648 | * - otherwise, we print a cross. |
649 | */ |
650 | if (classes[0] == classes[1] && |
651 | classes[1] == classes[2] && |
652 | classes[2] == classes[3]) |
653 | printf(" "); |
654 | else if (classes[0] == classes[1] && |
655 | classes[2] == classes[3]) |
656 | printf("-"); |
657 | else if (classes[0] == classes[2] && |
658 | classes[1] == classes[3]) |
659 | printf("|"); |
660 | else |
661 | printf("+"); |
662 | break; |
663 | case 1: /* horiz edge */ |
664 | if (classes[1] == classes[3]) |
665 | printf(" "); |
666 | else |
667 | printf("--"); |
668 | break; |
669 | case 2: /* vert edge */ |
670 | if (classes[2] == classes[3]) |
671 | printf(" "); |
672 | else |
673 | printf("|"); |
674 | break; |
675 | case 3: /* square centre */ |
676 | printf(" "); |
677 | break; |
11d273f7 |
678 | } |
11d273f7 |
679 | } |
680 | printf("\n"); |
11d273f7 |
681 | } |
9d36cbd7 |
682 | printf("\n"); |
683 | sfree(dsf); |
11d273f7 |
684 | } |
685 | |
9d36cbd7 |
686 | printf("%d retries needed for %d successes\n", fail_counter, tries); |
11d273f7 |
687 | |
688 | return 0; |
689 | } |
690 | |
691 | #endif |