| 1 | /* |
| 2 | * solo.c: the number-placing puzzle most popularly known as `Sudoku'. |
| 3 | * |
| 4 | * TODO: |
| 5 | * |
| 6 | * - it might still be nice to do some prioritisation on the |
| 7 | * removal of numbers from the grid |
| 8 | * + one possibility is to try to minimise the maximum number |
| 9 | * of filled squares in any block, which in particular ought |
| 10 | * to enforce never leaving a completely filled block in the |
| 11 | * puzzle as presented. |
| 12 | * |
| 13 | * - alternative interface modes |
| 14 | * + sudoku.com's Windows program has a palette of possible |
| 15 | * entries; you select a palette entry first and then click |
| 16 | * on the square you want it to go in, thus enabling |
| 17 | * mouse-only play. Useful for PDAs! I don't think it's |
| 18 | * actually incompatible with the current highlight-then-type |
| 19 | * approach: you _either_ highlight a palette entry and then |
| 20 | * click, _or_ you highlight a square and then type. At most |
| 21 | * one thing is ever highlighted at a time, so there's no way |
| 22 | * to confuse the two. |
| 23 | * + `pencil marks' might be useful for more subtle forms of |
| 24 | * deduction, now we can create puzzles that require them. |
| 25 | */ |
| 26 | |
| 27 | /* |
| 28 | * Solo puzzles need to be square overall (since each row and each |
| 29 | * column must contain one of every digit), but they need not be |
| 30 | * subdivided the same way internally. I am going to adopt a |
| 31 | * convention whereby I _always_ refer to `r' as the number of rows |
| 32 | * of _big_ divisions, and `c' as the number of columns of _big_ |
| 33 | * divisions. Thus, a 2c by 3r puzzle looks something like this: |
| 34 | * |
| 35 | * 4 5 1 | 2 6 3 |
| 36 | * 6 3 2 | 5 4 1 |
| 37 | * ------+------ (Of course, you can't subdivide it the other way |
| 38 | * 1 4 5 | 6 3 2 or you'll get clashes; observe that the 4 in the |
| 39 | * 3 2 6 | 4 1 5 top left would conflict with the 4 in the second |
| 40 | * ------+------ box down on the left-hand side.) |
| 41 | * 5 1 4 | 3 2 6 |
| 42 | * 2 6 3 | 1 5 4 |
| 43 | * |
| 44 | * The need for a strong naming convention should now be clear: |
| 45 | * each small box is two rows of digits by three columns, while the |
| 46 | * overall puzzle has three rows of small boxes by two columns. So |
| 47 | * I will (hopefully) consistently use `r' to denote the number of |
| 48 | * rows _of small boxes_ (here 3), which is also the number of |
| 49 | * columns of digits in each small box; and `c' vice versa (here |
| 50 | * 2). |
| 51 | * |
| 52 | * I'm also going to choose arbitrarily to list c first wherever |
| 53 | * possible: the above is a 2x3 puzzle, not a 3x2 one. |
| 54 | */ |
| 55 | |
| 56 | #include <stdio.h> |
| 57 | #include <stdlib.h> |
| 58 | #include <string.h> |
| 59 | #include <assert.h> |
| 60 | #include <ctype.h> |
| 61 | #include <math.h> |
| 62 | |
| 63 | #ifdef STANDALONE_SOLVER |
| 64 | #include <stdarg.h> |
| 65 | int solver_show_working; |
| 66 | #endif |
| 67 | |
| 68 | #include "puzzles.h" |
| 69 | |
| 70 | #define max(x,y) ((x)>(y)?(x):(y)) |
| 71 | |
| 72 | /* |
| 73 | * To save space, I store digits internally as unsigned char. This |
| 74 | * imposes a hard limit of 255 on the order of the puzzle. Since |
| 75 | * even a 5x5 takes unacceptably long to generate, I don't see this |
| 76 | * as a serious limitation unless something _really_ impressive |
| 77 | * happens in computing technology; but here's a typedef anyway for |
| 78 | * general good practice. |
| 79 | */ |
| 80 | typedef unsigned char digit; |
| 81 | #define ORDER_MAX 255 |
| 82 | |
| 83 | #define TILE_SIZE 32 |
| 84 | #define BORDER 18 |
| 85 | |
| 86 | #define FLASH_TIME 0.4F |
| 87 | |
| 88 | enum { SYMM_NONE, SYMM_ROT2, SYMM_ROT4, SYMM_REF4 }; |
| 89 | |
| 90 | enum { DIFF_BLOCK, DIFF_SIMPLE, DIFF_INTERSECT, |
| 91 | DIFF_SET, DIFF_RECURSIVE, DIFF_AMBIGUOUS, DIFF_IMPOSSIBLE }; |
| 92 | |
| 93 | enum { |
| 94 | COL_BACKGROUND, |
| 95 | COL_GRID, |
| 96 | COL_CLUE, |
| 97 | COL_USER, |
| 98 | COL_HIGHLIGHT, |
| 99 | NCOLOURS |
| 100 | }; |
| 101 | |
| 102 | struct game_params { |
| 103 | int c, r, symm, diff; |
| 104 | }; |
| 105 | |
| 106 | struct game_state { |
| 107 | int c, r; |
| 108 | digit *grid; |
| 109 | unsigned char *immutable; /* marks which digits are clues */ |
| 110 | int completed, cheated; |
| 111 | }; |
| 112 | |
| 113 | static game_params *default_params(void) |
| 114 | { |
| 115 | game_params *ret = snew(game_params); |
| 116 | |
| 117 | ret->c = ret->r = 3; |
| 118 | ret->symm = SYMM_ROT2; /* a plausible default */ |
| 119 | ret->diff = DIFF_BLOCK; /* so is this */ |
| 120 | |
| 121 | return ret; |
| 122 | } |
| 123 | |
| 124 | static void free_params(game_params *params) |
| 125 | { |
| 126 | sfree(params); |
| 127 | } |
| 128 | |
| 129 | static game_params *dup_params(game_params *params) |
| 130 | { |
| 131 | game_params *ret = snew(game_params); |
| 132 | *ret = *params; /* structure copy */ |
| 133 | return ret; |
| 134 | } |
| 135 | |
| 136 | static int game_fetch_preset(int i, char **name, game_params **params) |
| 137 | { |
| 138 | static struct { |
| 139 | char *title; |
| 140 | game_params params; |
| 141 | } presets[] = { |
| 142 | { "2x2 Trivial", { 2, 2, SYMM_ROT2, DIFF_BLOCK } }, |
| 143 | { "2x3 Basic", { 2, 3, SYMM_ROT2, DIFF_SIMPLE } }, |
| 144 | { "3x3 Trivial", { 3, 3, SYMM_ROT2, DIFF_BLOCK } }, |
| 145 | { "3x3 Basic", { 3, 3, SYMM_ROT2, DIFF_SIMPLE } }, |
| 146 | { "3x3 Intermediate", { 3, 3, SYMM_ROT2, DIFF_INTERSECT } }, |
| 147 | { "3x3 Advanced", { 3, 3, SYMM_ROT2, DIFF_SET } }, |
| 148 | { "3x3 Unreasonable", { 3, 3, SYMM_ROT2, DIFF_RECURSIVE } }, |
| 149 | { "3x4 Basic", { 3, 4, SYMM_ROT2, DIFF_SIMPLE } }, |
| 150 | { "4x4 Basic", { 4, 4, SYMM_ROT2, DIFF_SIMPLE } }, |
| 151 | }; |
| 152 | |
| 153 | if (i < 0 || i >= lenof(presets)) |
| 154 | return FALSE; |
| 155 | |
| 156 | *name = dupstr(presets[i].title); |
| 157 | *params = dup_params(&presets[i].params); |
| 158 | |
| 159 | return TRUE; |
| 160 | } |
| 161 | |
| 162 | static game_params *decode_params(char const *string) |
| 163 | { |
| 164 | game_params *ret = default_params(); |
| 165 | |
| 166 | ret->c = ret->r = atoi(string); |
| 167 | ret->symm = SYMM_ROT2; |
| 168 | ret->diff = DIFF_BLOCK; |
| 169 | while (*string && isdigit((unsigned char)*string)) string++; |
| 170 | if (*string == 'x') { |
| 171 | string++; |
| 172 | ret->r = atoi(string); |
| 173 | while (*string && isdigit((unsigned char)*string)) string++; |
| 174 | } |
| 175 | while (*string) { |
| 176 | if (*string == 'r' || *string == 'm' || *string == 'a') { |
| 177 | int sn, sc; |
| 178 | sc = *string++; |
| 179 | sn = atoi(string); |
| 180 | while (*string && isdigit((unsigned char)*string)) string++; |
| 181 | if (sc == 'm' && sn == 4) |
| 182 | ret->symm = SYMM_REF4; |
| 183 | if (sc == 'r' && sn == 4) |
| 184 | ret->symm = SYMM_ROT4; |
| 185 | if (sc == 'r' && sn == 2) |
| 186 | ret->symm = SYMM_ROT2; |
| 187 | if (sc == 'a') |
| 188 | ret->symm = SYMM_NONE; |
| 189 | } else if (*string == 'd') { |
| 190 | string++; |
| 191 | if (*string == 't') /* trivial */ |
| 192 | string++, ret->diff = DIFF_BLOCK; |
| 193 | else if (*string == 'b') /* basic */ |
| 194 | string++, ret->diff = DIFF_SIMPLE; |
| 195 | else if (*string == 'i') /* intermediate */ |
| 196 | string++, ret->diff = DIFF_INTERSECT; |
| 197 | else if (*string == 'a') /* advanced */ |
| 198 | string++, ret->diff = DIFF_SET; |
| 199 | else if (*string == 'u') /* unreasonable */ |
| 200 | string++, ret->diff = DIFF_RECURSIVE; |
| 201 | } else |
| 202 | string++; /* eat unknown character */ |
| 203 | } |
| 204 | |
| 205 | return ret; |
| 206 | } |
| 207 | |
| 208 | static char *encode_params(game_params *params) |
| 209 | { |
| 210 | char str[80]; |
| 211 | |
| 212 | /* |
| 213 | * Symmetry is a game generation preference and hence is left |
| 214 | * out of the encoding. Users can add it back in as they see |
| 215 | * fit. |
| 216 | */ |
| 217 | sprintf(str, "%dx%d", params->c, params->r); |
| 218 | return dupstr(str); |
| 219 | } |
| 220 | |
| 221 | static config_item *game_configure(game_params *params) |
| 222 | { |
| 223 | config_item *ret; |
| 224 | char buf[80]; |
| 225 | |
| 226 | ret = snewn(5, config_item); |
| 227 | |
| 228 | ret[0].name = "Columns of sub-blocks"; |
| 229 | ret[0].type = C_STRING; |
| 230 | sprintf(buf, "%d", params->c); |
| 231 | ret[0].sval = dupstr(buf); |
| 232 | ret[0].ival = 0; |
| 233 | |
| 234 | ret[1].name = "Rows of sub-blocks"; |
| 235 | ret[1].type = C_STRING; |
| 236 | sprintf(buf, "%d", params->r); |
| 237 | ret[1].sval = dupstr(buf); |
| 238 | ret[1].ival = 0; |
| 239 | |
| 240 | ret[2].name = "Symmetry"; |
| 241 | ret[2].type = C_CHOICES; |
| 242 | ret[2].sval = ":None:2-way rotation:4-way rotation:4-way mirror"; |
| 243 | ret[2].ival = params->symm; |
| 244 | |
| 245 | ret[3].name = "Difficulty"; |
| 246 | ret[3].type = C_CHOICES; |
| 247 | ret[3].sval = ":Trivial:Basic:Intermediate:Advanced:Unreasonable"; |
| 248 | ret[3].ival = params->diff; |
| 249 | |
| 250 | ret[4].name = NULL; |
| 251 | ret[4].type = C_END; |
| 252 | ret[4].sval = NULL; |
| 253 | ret[4].ival = 0; |
| 254 | |
| 255 | return ret; |
| 256 | } |
| 257 | |
| 258 | static game_params *custom_params(config_item *cfg) |
| 259 | { |
| 260 | game_params *ret = snew(game_params); |
| 261 | |
| 262 | ret->c = atoi(cfg[0].sval); |
| 263 | ret->r = atoi(cfg[1].sval); |
| 264 | ret->symm = cfg[2].ival; |
| 265 | ret->diff = cfg[3].ival; |
| 266 | |
| 267 | return ret; |
| 268 | } |
| 269 | |
| 270 | static char *validate_params(game_params *params) |
| 271 | { |
| 272 | if (params->c < 2 || params->r < 2) |
| 273 | return "Both dimensions must be at least 2"; |
| 274 | if (params->c > ORDER_MAX || params->r > ORDER_MAX) |
| 275 | return "Dimensions greater than "STR(ORDER_MAX)" are not supported"; |
| 276 | return NULL; |
| 277 | } |
| 278 | |
| 279 | /* ---------------------------------------------------------------------- |
| 280 | * Full recursive Solo solver. |
| 281 | * |
| 282 | * The algorithm for this solver is shamelessly copied from a |
| 283 | * Python solver written by Andrew Wilkinson (which is GPLed, but |
| 284 | * I've reused only ideas and no code). It mostly just does the |
| 285 | * obvious recursive thing: pick an empty square, put one of the |
| 286 | * possible digits in it, recurse until all squares are filled, |
| 287 | * backtrack and change some choices if necessary. |
| 288 | * |
| 289 | * The clever bit is that every time it chooses which square to |
| 290 | * fill in next, it does so by counting the number of _possible_ |
| 291 | * numbers that can go in each square, and it prioritises so that |
| 292 | * it picks a square with the _lowest_ number of possibilities. The |
| 293 | * idea is that filling in lots of the obvious bits (particularly |
| 294 | * any squares with only one possibility) will cut down on the list |
| 295 | * of possibilities for other squares and hence reduce the enormous |
| 296 | * search space as much as possible as early as possible. |
| 297 | * |
| 298 | * In practice the algorithm appeared to work very well; run on |
| 299 | * sample problems from the Times it completed in well under a |
| 300 | * second on my G5 even when written in Python, and given an empty |
| 301 | * grid (so that in principle it would enumerate _all_ solved |
| 302 | * grids!) it found the first valid solution just as quickly. So |
| 303 | * with a bit more randomisation I see no reason not to use this as |
| 304 | * my grid generator. |
| 305 | */ |
| 306 | |
| 307 | /* |
| 308 | * Internal data structure used in solver to keep track of |
| 309 | * progress. |
| 310 | */ |
| 311 | struct rsolve_coord { int x, y, r; }; |
| 312 | struct rsolve_usage { |
| 313 | int c, r, cr; /* cr == c*r */ |
| 314 | /* grid is a copy of the input grid, modified as we go along */ |
| 315 | digit *grid; |
| 316 | /* row[y*cr+n-1] TRUE if digit n has been placed in row y */ |
| 317 | unsigned char *row; |
| 318 | /* col[x*cr+n-1] TRUE if digit n has been placed in row x */ |
| 319 | unsigned char *col; |
| 320 | /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */ |
| 321 | unsigned char *blk; |
| 322 | /* This lists all the empty spaces remaining in the grid. */ |
| 323 | struct rsolve_coord *spaces; |
| 324 | int nspaces; |
| 325 | /* If we need randomisation in the solve, this is our random state. */ |
| 326 | random_state *rs; |
| 327 | /* Number of solutions so far found, and maximum number we care about. */ |
| 328 | int solns, maxsolns; |
| 329 | }; |
| 330 | |
| 331 | /* |
| 332 | * The real recursive step in the solving function. |
| 333 | */ |
| 334 | static void rsolve_real(struct rsolve_usage *usage, digit *grid) |
| 335 | { |
| 336 | int c = usage->c, r = usage->r, cr = usage->cr; |
| 337 | int i, j, n, sx, sy, bestm, bestr; |
| 338 | int *digits; |
| 339 | |
| 340 | /* |
| 341 | * Firstly, check for completion! If there are no spaces left |
| 342 | * in the grid, we have a solution. |
| 343 | */ |
| 344 | if (usage->nspaces == 0) { |
| 345 | if (!usage->solns) { |
| 346 | /* |
| 347 | * This is our first solution, so fill in the output grid. |
| 348 | */ |
| 349 | memcpy(grid, usage->grid, cr * cr); |
| 350 | } |
| 351 | usage->solns++; |
| 352 | return; |
| 353 | } |
| 354 | |
| 355 | /* |
| 356 | * Otherwise, there must be at least one space. Find the most |
| 357 | * constrained space, using the `r' field as a tie-breaker. |
| 358 | */ |
| 359 | bestm = cr+1; /* so that any space will beat it */ |
| 360 | bestr = 0; |
| 361 | i = sx = sy = -1; |
| 362 | for (j = 0; j < usage->nspaces; j++) { |
| 363 | int x = usage->spaces[j].x, y = usage->spaces[j].y; |
| 364 | int m; |
| 365 | |
| 366 | /* |
| 367 | * Find the number of digits that could go in this space. |
| 368 | */ |
| 369 | m = 0; |
| 370 | for (n = 0; n < cr; n++) |
| 371 | if (!usage->row[y*cr+n] && !usage->col[x*cr+n] && |
| 372 | !usage->blk[((y/c)*c+(x/r))*cr+n]) |
| 373 | m++; |
| 374 | |
| 375 | if (m < bestm || (m == bestm && usage->spaces[j].r < bestr)) { |
| 376 | bestm = m; |
| 377 | bestr = usage->spaces[j].r; |
| 378 | sx = x; |
| 379 | sy = y; |
| 380 | i = j; |
| 381 | } |
| 382 | } |
| 383 | |
| 384 | /* |
| 385 | * Swap that square into the final place in the spaces array, |
| 386 | * so that decrementing nspaces will remove it from the list. |
| 387 | */ |
| 388 | if (i != usage->nspaces-1) { |
| 389 | struct rsolve_coord t; |
| 390 | t = usage->spaces[usage->nspaces-1]; |
| 391 | usage->spaces[usage->nspaces-1] = usage->spaces[i]; |
| 392 | usage->spaces[i] = t; |
| 393 | } |
| 394 | |
| 395 | /* |
| 396 | * Now we've decided which square to start our recursion at, |
| 397 | * simply go through all possible values, shuffling them |
| 398 | * randomly first if necessary. |
| 399 | */ |
| 400 | digits = snewn(bestm, int); |
| 401 | j = 0; |
| 402 | for (n = 0; n < cr; n++) |
| 403 | if (!usage->row[sy*cr+n] && !usage->col[sx*cr+n] && |
| 404 | !usage->blk[((sy/c)*c+(sx/r))*cr+n]) { |
| 405 | digits[j++] = n+1; |
| 406 | } |
| 407 | |
| 408 | if (usage->rs) { |
| 409 | /* shuffle */ |
| 410 | for (i = j; i > 1; i--) { |
| 411 | int p = random_upto(usage->rs, i); |
| 412 | if (p != i-1) { |
| 413 | int t = digits[p]; |
| 414 | digits[p] = digits[i-1]; |
| 415 | digits[i-1] = t; |
| 416 | } |
| 417 | } |
| 418 | } |
| 419 | |
| 420 | /* And finally, go through the digit list and actually recurse. */ |
| 421 | for (i = 0; i < j; i++) { |
| 422 | n = digits[i]; |
| 423 | |
| 424 | /* Update the usage structure to reflect the placing of this digit. */ |
| 425 | usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] = |
| 426 | usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = TRUE; |
| 427 | usage->grid[sy*cr+sx] = n; |
| 428 | usage->nspaces--; |
| 429 | |
| 430 | /* Call the solver recursively. */ |
| 431 | rsolve_real(usage, grid); |
| 432 | |
| 433 | /* |
| 434 | * If we have seen as many solutions as we need, terminate |
| 435 | * all processing immediately. |
| 436 | */ |
| 437 | if (usage->solns >= usage->maxsolns) |
| 438 | break; |
| 439 | |
| 440 | /* Revert the usage structure. */ |
| 441 | usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] = |
| 442 | usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = FALSE; |
| 443 | usage->grid[sy*cr+sx] = 0; |
| 444 | usage->nspaces++; |
| 445 | } |
| 446 | |
| 447 | sfree(digits); |
| 448 | } |
| 449 | |
| 450 | /* |
| 451 | * Entry point to solver. You give it dimensions and a starting |
| 452 | * grid, which is simply an array of N^4 digits. In that array, 0 |
| 453 | * means an empty square, and 1..N mean a clue square. |
| 454 | * |
| 455 | * Return value is the number of solutions found; searching will |
| 456 | * stop after the provided `max'. (Thus, you can pass max==1 to |
| 457 | * indicate that you only care about finding _one_ solution, or |
| 458 | * max==2 to indicate that you want to know the difference between |
| 459 | * a unique and non-unique solution.) The input parameter `grid' is |
| 460 | * also filled in with the _first_ (or only) solution found by the |
| 461 | * solver. |
| 462 | */ |
| 463 | static int rsolve(int c, int r, digit *grid, random_state *rs, int max) |
| 464 | { |
| 465 | struct rsolve_usage *usage; |
| 466 | int x, y, cr = c*r; |
| 467 | int ret; |
| 468 | |
| 469 | /* |
| 470 | * Create an rsolve_usage structure. |
| 471 | */ |
| 472 | usage = snew(struct rsolve_usage); |
| 473 | |
| 474 | usage->c = c; |
| 475 | usage->r = r; |
| 476 | usage->cr = cr; |
| 477 | |
| 478 | usage->grid = snewn(cr * cr, digit); |
| 479 | memcpy(usage->grid, grid, cr * cr); |
| 480 | |
| 481 | usage->row = snewn(cr * cr, unsigned char); |
| 482 | usage->col = snewn(cr * cr, unsigned char); |
| 483 | usage->blk = snewn(cr * cr, unsigned char); |
| 484 | memset(usage->row, FALSE, cr * cr); |
| 485 | memset(usage->col, FALSE, cr * cr); |
| 486 | memset(usage->blk, FALSE, cr * cr); |
| 487 | |
| 488 | usage->spaces = snewn(cr * cr, struct rsolve_coord); |
| 489 | usage->nspaces = 0; |
| 490 | |
| 491 | usage->solns = 0; |
| 492 | usage->maxsolns = max; |
| 493 | |
| 494 | usage->rs = rs; |
| 495 | |
| 496 | /* |
| 497 | * Now fill it in with data from the input grid. |
| 498 | */ |
| 499 | for (y = 0; y < cr; y++) { |
| 500 | for (x = 0; x < cr; x++) { |
| 501 | int v = grid[y*cr+x]; |
| 502 | if (v == 0) { |
| 503 | usage->spaces[usage->nspaces].x = x; |
| 504 | usage->spaces[usage->nspaces].y = y; |
| 505 | if (rs) |
| 506 | usage->spaces[usage->nspaces].r = random_bits(rs, 31); |
| 507 | else |
| 508 | usage->spaces[usage->nspaces].r = usage->nspaces; |
| 509 | usage->nspaces++; |
| 510 | } else { |
| 511 | usage->row[y*cr+v-1] = TRUE; |
| 512 | usage->col[x*cr+v-1] = TRUE; |
| 513 | usage->blk[((y/c)*c+(x/r))*cr+v-1] = TRUE; |
| 514 | } |
| 515 | } |
| 516 | } |
| 517 | |
| 518 | /* |
| 519 | * Run the real recursive solving function. |
| 520 | */ |
| 521 | rsolve_real(usage, grid); |
| 522 | ret = usage->solns; |
| 523 | |
| 524 | /* |
| 525 | * Clean up the usage structure now we have our answer. |
| 526 | */ |
| 527 | sfree(usage->spaces); |
| 528 | sfree(usage->blk); |
| 529 | sfree(usage->col); |
| 530 | sfree(usage->row); |
| 531 | sfree(usage->grid); |
| 532 | sfree(usage); |
| 533 | |
| 534 | /* |
| 535 | * And return. |
| 536 | */ |
| 537 | return ret; |
| 538 | } |
| 539 | |
| 540 | /* ---------------------------------------------------------------------- |
| 541 | * End of recursive solver code. |
| 542 | */ |
| 543 | |
| 544 | /* ---------------------------------------------------------------------- |
| 545 | * Less capable non-recursive solver. This one is used to check |
| 546 | * solubility of a grid as we gradually remove numbers from it: by |
| 547 | * verifying a grid using this solver we can ensure it isn't _too_ |
| 548 | * hard (e.g. does not actually require guessing and backtracking). |
| 549 | * |
| 550 | * It supports a variety of specific modes of reasoning. By |
| 551 | * enabling or disabling subsets of these modes we can arrange a |
| 552 | * range of difficulty levels. |
| 553 | */ |
| 554 | |
| 555 | /* |
| 556 | * Modes of reasoning currently supported: |
| 557 | * |
| 558 | * - Positional elimination: a number must go in a particular |
| 559 | * square because all the other empty squares in a given |
| 560 | * row/col/blk are ruled out. |
| 561 | * |
| 562 | * - Numeric elimination: a square must have a particular number |
| 563 | * in because all the other numbers that could go in it are |
| 564 | * ruled out. |
| 565 | * |
| 566 | * - Intersectional analysis: given two domains which overlap |
| 567 | * (hence one must be a block, and the other can be a row or |
| 568 | * col), if the possible locations for a particular number in |
| 569 | * one of the domains can be narrowed down to the overlap, then |
| 570 | * that number can be ruled out everywhere but the overlap in |
| 571 | * the other domain too. |
| 572 | * |
| 573 | * - Set elimination: if there is a subset of the empty squares |
| 574 | * within a domain such that the union of the possible numbers |
| 575 | * in that subset has the same size as the subset itself, then |
| 576 | * those numbers can be ruled out everywhere else in the domain. |
| 577 | * (For example, if there are five empty squares and the |
| 578 | * possible numbers in each are 12, 23, 13, 134 and 1345, then |
| 579 | * the first three empty squares form such a subset: the numbers |
| 580 | * 1, 2 and 3 _must_ be in those three squares in some |
| 581 | * permutation, and hence we can deduce none of them can be in |
| 582 | * the fourth or fifth squares.) |
| 583 | * + You can also see this the other way round, concentrating |
| 584 | * on numbers rather than squares: if there is a subset of |
| 585 | * the unplaced numbers within a domain such that the union |
| 586 | * of all their possible positions has the same size as the |
| 587 | * subset itself, then all other numbers can be ruled out for |
| 588 | * those positions. However, it turns out that this is |
| 589 | * exactly equivalent to the first formulation at all times: |
| 590 | * there is a 1-1 correspondence between suitable subsets of |
| 591 | * the unplaced numbers and suitable subsets of the unfilled |
| 592 | * places, found by taking the _complement_ of the union of |
| 593 | * the numbers' possible positions (or the spaces' possible |
| 594 | * contents). |
| 595 | */ |
| 596 | |
| 597 | /* |
| 598 | * Within this solver, I'm going to transform all y-coordinates by |
| 599 | * inverting the significance of the block number and the position |
| 600 | * within the block. That is, we will start with the top row of |
| 601 | * each block in order, then the second row of each block in order, |
| 602 | * etc. |
| 603 | * |
| 604 | * This transformation has the enormous advantage that it means |
| 605 | * every row, column _and_ block is described by an arithmetic |
| 606 | * progression of coordinates within the cubic array, so that I can |
| 607 | * use the same very simple function to do blockwise, row-wise and |
| 608 | * column-wise elimination. |
| 609 | */ |
| 610 | #define YTRANS(y) (((y)%c)*r+(y)/c) |
| 611 | #define YUNTRANS(y) (((y)%r)*c+(y)/r) |
| 612 | |
| 613 | struct nsolve_usage { |
| 614 | int c, r, cr; |
| 615 | /* |
| 616 | * We set up a cubic array, indexed by x, y and digit; each |
| 617 | * element of this array is TRUE or FALSE according to whether |
| 618 | * or not that digit _could_ in principle go in that position. |
| 619 | * |
| 620 | * The way to index this array is cube[(x*cr+y)*cr+n-1]. |
| 621 | * y-coordinates in here are transformed. |
| 622 | */ |
| 623 | unsigned char *cube; |
| 624 | /* |
| 625 | * This is the grid in which we write down our final |
| 626 | * deductions. y-coordinates in here are _not_ transformed. |
| 627 | */ |
| 628 | digit *grid; |
| 629 | /* |
| 630 | * Now we keep track, at a slightly higher level, of what we |
| 631 | * have yet to work out, to prevent doing the same deduction |
| 632 | * many times. |
| 633 | */ |
| 634 | /* row[y*cr+n-1] TRUE if digit n has been placed in row y */ |
| 635 | unsigned char *row; |
| 636 | /* col[x*cr+n-1] TRUE if digit n has been placed in row x */ |
| 637 | unsigned char *col; |
| 638 | /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */ |
| 639 | unsigned char *blk; |
| 640 | }; |
| 641 | #define cubepos(x,y,n) (((x)*usage->cr+(y))*usage->cr+(n)-1) |
| 642 | #define cube(x,y,n) (usage->cube[cubepos(x,y,n)]) |
| 643 | |
| 644 | /* |
| 645 | * Function called when we are certain that a particular square has |
| 646 | * a particular number in it. The y-coordinate passed in here is |
| 647 | * transformed. |
| 648 | */ |
| 649 | static void nsolve_place(struct nsolve_usage *usage, int x, int y, int n) |
| 650 | { |
| 651 | int c = usage->c, r = usage->r, cr = usage->cr; |
| 652 | int i, j, bx, by; |
| 653 | |
| 654 | assert(cube(x,y,n)); |
| 655 | |
| 656 | /* |
| 657 | * Rule out all other numbers in this square. |
| 658 | */ |
| 659 | for (i = 1; i <= cr; i++) |
| 660 | if (i != n) |
| 661 | cube(x,y,i) = FALSE; |
| 662 | |
| 663 | /* |
| 664 | * Rule out this number in all other positions in the row. |
| 665 | */ |
| 666 | for (i = 0; i < cr; i++) |
| 667 | if (i != y) |
| 668 | cube(x,i,n) = FALSE; |
| 669 | |
| 670 | /* |
| 671 | * Rule out this number in all other positions in the column. |
| 672 | */ |
| 673 | for (i = 0; i < cr; i++) |
| 674 | if (i != x) |
| 675 | cube(i,y,n) = FALSE; |
| 676 | |
| 677 | /* |
| 678 | * Rule out this number in all other positions in the block. |
| 679 | */ |
| 680 | bx = (x/r)*r; |
| 681 | by = y % r; |
| 682 | for (i = 0; i < r; i++) |
| 683 | for (j = 0; j < c; j++) |
| 684 | if (bx+i != x || by+j*r != y) |
| 685 | cube(bx+i,by+j*r,n) = FALSE; |
| 686 | |
| 687 | /* |
| 688 | * Enter the number in the result grid. |
| 689 | */ |
| 690 | usage->grid[YUNTRANS(y)*cr+x] = n; |
| 691 | |
| 692 | /* |
| 693 | * Cross out this number from the list of numbers left to place |
| 694 | * in its row, its column and its block. |
| 695 | */ |
| 696 | usage->row[y*cr+n-1] = usage->col[x*cr+n-1] = |
| 697 | usage->blk[((y%r)*c+(x/r))*cr+n-1] = TRUE; |
| 698 | } |
| 699 | |
| 700 | static int nsolve_elim(struct nsolve_usage *usage, int start, int step |
| 701 | #ifdef STANDALONE_SOLVER |
| 702 | , char *fmt, ... |
| 703 | #endif |
| 704 | ) |
| 705 | { |
| 706 | int c = usage->c, r = usage->r, cr = c*r; |
| 707 | int fpos, m, i; |
| 708 | |
| 709 | /* |
| 710 | * Count the number of set bits within this section of the |
| 711 | * cube. |
| 712 | */ |
| 713 | m = 0; |
| 714 | fpos = -1; |
| 715 | for (i = 0; i < cr; i++) |
| 716 | if (usage->cube[start+i*step]) { |
| 717 | fpos = start+i*step; |
| 718 | m++; |
| 719 | } |
| 720 | |
| 721 | if (m == 1) { |
| 722 | int x, y, n; |
| 723 | assert(fpos >= 0); |
| 724 | |
| 725 | n = 1 + fpos % cr; |
| 726 | y = fpos / cr; |
| 727 | x = y / cr; |
| 728 | y %= cr; |
| 729 | |
| 730 | if (!usage->grid[YUNTRANS(y)*cr+x]) { |
| 731 | #ifdef STANDALONE_SOLVER |
| 732 | if (solver_show_working) { |
| 733 | va_list ap; |
| 734 | va_start(ap, fmt); |
| 735 | vprintf(fmt, ap); |
| 736 | va_end(ap); |
| 737 | printf(":\n placing %d at (%d,%d)\n", |
| 738 | n, 1+x, 1+YUNTRANS(y)); |
| 739 | } |
| 740 | #endif |
| 741 | nsolve_place(usage, x, y, n); |
| 742 | return TRUE; |
| 743 | } |
| 744 | } |
| 745 | |
| 746 | return FALSE; |
| 747 | } |
| 748 | |
| 749 | static int nsolve_intersect(struct nsolve_usage *usage, |
| 750 | int start1, int step1, int start2, int step2 |
| 751 | #ifdef STANDALONE_SOLVER |
| 752 | , char *fmt, ... |
| 753 | #endif |
| 754 | ) |
| 755 | { |
| 756 | int c = usage->c, r = usage->r, cr = c*r; |
| 757 | int ret, i; |
| 758 | |
| 759 | /* |
| 760 | * Loop over the first domain and see if there's any set bit |
| 761 | * not also in the second. |
| 762 | */ |
| 763 | for (i = 0; i < cr; i++) { |
| 764 | int p = start1+i*step1; |
| 765 | if (usage->cube[p] && |
| 766 | !(p >= start2 && p < start2+cr*step2 && |
| 767 | (p - start2) % step2 == 0)) |
| 768 | return FALSE; /* there is, so we can't deduce */ |
| 769 | } |
| 770 | |
| 771 | /* |
| 772 | * We have determined that all set bits in the first domain are |
| 773 | * within its overlap with the second. So loop over the second |
| 774 | * domain and remove all set bits that aren't also in that |
| 775 | * overlap; return TRUE iff we actually _did_ anything. |
| 776 | */ |
| 777 | ret = FALSE; |
| 778 | for (i = 0; i < cr; i++) { |
| 779 | int p = start2+i*step2; |
| 780 | if (usage->cube[p] && |
| 781 | !(p >= start1 && p < start1+cr*step1 && (p - start1) % step1 == 0)) |
| 782 | { |
| 783 | #ifdef STANDALONE_SOLVER |
| 784 | if (solver_show_working) { |
| 785 | int px, py, pn; |
| 786 | |
| 787 | if (!ret) { |
| 788 | va_list ap; |
| 789 | va_start(ap, fmt); |
| 790 | vprintf(fmt, ap); |
| 791 | va_end(ap); |
| 792 | printf(":\n"); |
| 793 | } |
| 794 | |
| 795 | pn = 1 + p % cr; |
| 796 | py = p / cr; |
| 797 | px = py / cr; |
| 798 | py %= cr; |
| 799 | |
| 800 | printf(" ruling out %d at (%d,%d)\n", |
| 801 | pn, 1+px, 1+YUNTRANS(py)); |
| 802 | } |
| 803 | #endif |
| 804 | ret = TRUE; /* we did something */ |
| 805 | usage->cube[p] = 0; |
| 806 | } |
| 807 | } |
| 808 | |
| 809 | return ret; |
| 810 | } |
| 811 | |
| 812 | static int nsolve_set(struct nsolve_usage *usage, |
| 813 | int start, int step1, int step2 |
| 814 | #ifdef STANDALONE_SOLVER |
| 815 | , char *fmt, ... |
| 816 | #endif |
| 817 | ) |
| 818 | { |
| 819 | int c = usage->c, r = usage->r, cr = c*r; |
| 820 | int i, j, n, count; |
| 821 | unsigned char *grid = snewn(cr*cr, unsigned char); |
| 822 | unsigned char *rowidx = snewn(cr, unsigned char); |
| 823 | unsigned char *colidx = snewn(cr, unsigned char); |
| 824 | unsigned char *set = snewn(cr, unsigned char); |
| 825 | |
| 826 | /* |
| 827 | * We are passed a cr-by-cr matrix of booleans. Our first job |
| 828 | * is to winnow it by finding any definite placements - i.e. |
| 829 | * any row with a solitary 1 - and discarding that row and the |
| 830 | * column containing the 1. |
| 831 | */ |
| 832 | memset(rowidx, TRUE, cr); |
| 833 | memset(colidx, TRUE, cr); |
| 834 | for (i = 0; i < cr; i++) { |
| 835 | int count = 0, first = -1; |
| 836 | for (j = 0; j < cr; j++) |
| 837 | if (usage->cube[start+i*step1+j*step2]) |
| 838 | first = j, count++; |
| 839 | if (count == 0) { |
| 840 | /* |
| 841 | * This condition actually marks a completely insoluble |
| 842 | * (i.e. internally inconsistent) puzzle. We return and |
| 843 | * report no progress made. |
| 844 | */ |
| 845 | return FALSE; |
| 846 | } |
| 847 | if (count == 1) |
| 848 | rowidx[i] = colidx[first] = FALSE; |
| 849 | } |
| 850 | |
| 851 | /* |
| 852 | * Convert each of rowidx/colidx from a list of 0s and 1s to a |
| 853 | * list of the indices of the 1s. |
| 854 | */ |
| 855 | for (i = j = 0; i < cr; i++) |
| 856 | if (rowidx[i]) |
| 857 | rowidx[j++] = i; |
| 858 | n = j; |
| 859 | for (i = j = 0; i < cr; i++) |
| 860 | if (colidx[i]) |
| 861 | colidx[j++] = i; |
| 862 | assert(n == j); |
| 863 | |
| 864 | /* |
| 865 | * And create the smaller matrix. |
| 866 | */ |
| 867 | for (i = 0; i < n; i++) |
| 868 | for (j = 0; j < n; j++) |
| 869 | grid[i*cr+j] = usage->cube[start+rowidx[i]*step1+colidx[j]*step2]; |
| 870 | |
| 871 | /* |
| 872 | * Having done that, we now have a matrix in which every row |
| 873 | * has at least two 1s in. Now we search to see if we can find |
| 874 | * a rectangle of zeroes (in the set-theoretic sense of |
| 875 | * `rectangle', i.e. a subset of rows crossed with a subset of |
| 876 | * columns) whose width and height add up to n. |
| 877 | */ |
| 878 | |
| 879 | memset(set, 0, n); |
| 880 | count = 0; |
| 881 | while (1) { |
| 882 | /* |
| 883 | * We have a candidate set. If its size is <=1 or >=n-1 |
| 884 | * then we move on immediately. |
| 885 | */ |
| 886 | if (count > 1 && count < n-1) { |
| 887 | /* |
| 888 | * The number of rows we need is n-count. See if we can |
| 889 | * find that many rows which each have a zero in all |
| 890 | * the positions listed in `set'. |
| 891 | */ |
| 892 | int rows = 0; |
| 893 | for (i = 0; i < n; i++) { |
| 894 | int ok = TRUE; |
| 895 | for (j = 0; j < n; j++) |
| 896 | if (set[j] && grid[i*cr+j]) { |
| 897 | ok = FALSE; |
| 898 | break; |
| 899 | } |
| 900 | if (ok) |
| 901 | rows++; |
| 902 | } |
| 903 | |
| 904 | /* |
| 905 | * We expect never to be able to get _more_ than |
| 906 | * n-count suitable rows: this would imply that (for |
| 907 | * example) there are four numbers which between them |
| 908 | * have at most three possible positions, and hence it |
| 909 | * indicates a faulty deduction before this point or |
| 910 | * even a bogus clue. |
| 911 | */ |
| 912 | assert(rows <= n - count); |
| 913 | if (rows >= n - count) { |
| 914 | int progress = FALSE; |
| 915 | |
| 916 | /* |
| 917 | * We've got one! Now, for each row which _doesn't_ |
| 918 | * satisfy the criterion, eliminate all its set |
| 919 | * bits in the positions _not_ listed in `set'. |
| 920 | * Return TRUE (meaning progress has been made) if |
| 921 | * we successfully eliminated anything at all. |
| 922 | * |
| 923 | * This involves referring back through |
| 924 | * rowidx/colidx in order to work out which actual |
| 925 | * positions in the cube to meddle with. |
| 926 | */ |
| 927 | for (i = 0; i < n; i++) { |
| 928 | int ok = TRUE; |
| 929 | for (j = 0; j < n; j++) |
| 930 | if (set[j] && grid[i*cr+j]) { |
| 931 | ok = FALSE; |
| 932 | break; |
| 933 | } |
| 934 | if (!ok) { |
| 935 | for (j = 0; j < n; j++) |
| 936 | if (!set[j] && grid[i*cr+j]) { |
| 937 | int fpos = (start+rowidx[i]*step1+ |
| 938 | colidx[j]*step2); |
| 939 | #ifdef STANDALONE_SOLVER |
| 940 | if (solver_show_working) { |
| 941 | int px, py, pn; |
| 942 | |
| 943 | if (!progress) { |
| 944 | va_list ap; |
| 945 | va_start(ap, fmt); |
| 946 | vprintf(fmt, ap); |
| 947 | va_end(ap); |
| 948 | printf(":\n"); |
| 949 | } |
| 950 | |
| 951 | pn = 1 + fpos % cr; |
| 952 | py = fpos / cr; |
| 953 | px = py / cr; |
| 954 | py %= cr; |
| 955 | |
| 956 | printf(" ruling out %d at (%d,%d)\n", |
| 957 | pn, 1+px, 1+YUNTRANS(py)); |
| 958 | } |
| 959 | #endif |
| 960 | progress = TRUE; |
| 961 | usage->cube[fpos] = FALSE; |
| 962 | } |
| 963 | } |
| 964 | } |
| 965 | |
| 966 | if (progress) { |
| 967 | sfree(set); |
| 968 | sfree(colidx); |
| 969 | sfree(rowidx); |
| 970 | sfree(grid); |
| 971 | return TRUE; |
| 972 | } |
| 973 | } |
| 974 | } |
| 975 | |
| 976 | /* |
| 977 | * Binary increment: change the rightmost 0 to a 1, and |
| 978 | * change all 1s to the right of it to 0s. |
| 979 | */ |
| 980 | i = n; |
| 981 | while (i > 0 && set[i-1]) |
| 982 | set[--i] = 0, count--; |
| 983 | if (i > 0) |
| 984 | set[--i] = 1, count++; |
| 985 | else |
| 986 | break; /* done */ |
| 987 | } |
| 988 | |
| 989 | sfree(set); |
| 990 | sfree(colidx); |
| 991 | sfree(rowidx); |
| 992 | sfree(grid); |
| 993 | |
| 994 | return FALSE; |
| 995 | } |
| 996 | |
| 997 | static int nsolve(int c, int r, digit *grid) |
| 998 | { |
| 999 | struct nsolve_usage *usage; |
| 1000 | int cr = c*r; |
| 1001 | int x, y, n; |
| 1002 | int diff = DIFF_BLOCK; |
| 1003 | |
| 1004 | /* |
| 1005 | * Set up a usage structure as a clean slate (everything |
| 1006 | * possible). |
| 1007 | */ |
| 1008 | usage = snew(struct nsolve_usage); |
| 1009 | usage->c = c; |
| 1010 | usage->r = r; |
| 1011 | usage->cr = cr; |
| 1012 | usage->cube = snewn(cr*cr*cr, unsigned char); |
| 1013 | usage->grid = grid; /* write straight back to the input */ |
| 1014 | memset(usage->cube, TRUE, cr*cr*cr); |
| 1015 | |
| 1016 | usage->row = snewn(cr * cr, unsigned char); |
| 1017 | usage->col = snewn(cr * cr, unsigned char); |
| 1018 | usage->blk = snewn(cr * cr, unsigned char); |
| 1019 | memset(usage->row, FALSE, cr * cr); |
| 1020 | memset(usage->col, FALSE, cr * cr); |
| 1021 | memset(usage->blk, FALSE, cr * cr); |
| 1022 | |
| 1023 | /* |
| 1024 | * Place all the clue numbers we are given. |
| 1025 | */ |
| 1026 | for (x = 0; x < cr; x++) |
| 1027 | for (y = 0; y < cr; y++) |
| 1028 | if (grid[y*cr+x]) |
| 1029 | nsolve_place(usage, x, YTRANS(y), grid[y*cr+x]); |
| 1030 | |
| 1031 | /* |
| 1032 | * Now loop over the grid repeatedly trying all permitted modes |
| 1033 | * of reasoning. The loop terminates if we complete an |
| 1034 | * iteration without making any progress; we then return |
| 1035 | * failure or success depending on whether the grid is full or |
| 1036 | * not. |
| 1037 | */ |
| 1038 | while (1) { |
| 1039 | /* |
| 1040 | * I'd like to write `continue;' inside each of the |
| 1041 | * following loops, so that the solver returns here after |
| 1042 | * making some progress. However, I can't specify that I |
| 1043 | * want to continue an outer loop rather than the innermost |
| 1044 | * one, so I'm apologetically resorting to a goto. |
| 1045 | */ |
| 1046 | cont: |
| 1047 | |
| 1048 | /* |
| 1049 | * Blockwise positional elimination. |
| 1050 | */ |
| 1051 | for (x = 0; x < cr; x += r) |
| 1052 | for (y = 0; y < r; y++) |
| 1053 | for (n = 1; n <= cr; n++) |
| 1054 | if (!usage->blk[(y*c+(x/r))*cr+n-1] && |
| 1055 | nsolve_elim(usage, cubepos(x,y,n), r*cr |
| 1056 | #ifdef STANDALONE_SOLVER |
| 1057 | , "positional elimination," |
| 1058 | " block (%d,%d)", 1+x/r, 1+y |
| 1059 | #endif |
| 1060 | )) { |
| 1061 | diff = max(diff, DIFF_BLOCK); |
| 1062 | goto cont; |
| 1063 | } |
| 1064 | |
| 1065 | /* |
| 1066 | * Row-wise positional elimination. |
| 1067 | */ |
| 1068 | for (y = 0; y < cr; y++) |
| 1069 | for (n = 1; n <= cr; n++) |
| 1070 | if (!usage->row[y*cr+n-1] && |
| 1071 | nsolve_elim(usage, cubepos(0,y,n), cr*cr |
| 1072 | #ifdef STANDALONE_SOLVER |
| 1073 | , "positional elimination," |
| 1074 | " row %d", 1+YUNTRANS(y) |
| 1075 | #endif |
| 1076 | )) { |
| 1077 | diff = max(diff, DIFF_SIMPLE); |
| 1078 | goto cont; |
| 1079 | } |
| 1080 | /* |
| 1081 | * Column-wise positional elimination. |
| 1082 | */ |
| 1083 | for (x = 0; x < cr; x++) |
| 1084 | for (n = 1; n <= cr; n++) |
| 1085 | if (!usage->col[x*cr+n-1] && |
| 1086 | nsolve_elim(usage, cubepos(x,0,n), cr |
| 1087 | #ifdef STANDALONE_SOLVER |
| 1088 | , "positional elimination," " column %d", 1+x |
| 1089 | #endif |
| 1090 | )) { |
| 1091 | diff = max(diff, DIFF_SIMPLE); |
| 1092 | goto cont; |
| 1093 | } |
| 1094 | |
| 1095 | /* |
| 1096 | * Numeric elimination. |
| 1097 | */ |
| 1098 | for (x = 0; x < cr; x++) |
| 1099 | for (y = 0; y < cr; y++) |
| 1100 | if (!usage->grid[YUNTRANS(y)*cr+x] && |
| 1101 | nsolve_elim(usage, cubepos(x,y,1), 1 |
| 1102 | #ifdef STANDALONE_SOLVER |
| 1103 | , "numeric elimination at (%d,%d)", 1+x, |
| 1104 | 1+YUNTRANS(y) |
| 1105 | #endif |
| 1106 | )) { |
| 1107 | diff = max(diff, DIFF_SIMPLE); |
| 1108 | goto cont; |
| 1109 | } |
| 1110 | |
| 1111 | /* |
| 1112 | * Intersectional analysis, rows vs blocks. |
| 1113 | */ |
| 1114 | for (y = 0; y < cr; y++) |
| 1115 | for (x = 0; x < cr; x += r) |
| 1116 | for (n = 1; n <= cr; n++) |
| 1117 | if (!usage->row[y*cr+n-1] && |
| 1118 | !usage->blk[((y%r)*c+(x/r))*cr+n-1] && |
| 1119 | (nsolve_intersect(usage, cubepos(0,y,n), cr*cr, |
| 1120 | cubepos(x,y%r,n), r*cr |
| 1121 | #ifdef STANDALONE_SOLVER |
| 1122 | , "intersectional analysis," |
| 1123 | " row %d vs block (%d,%d)", |
| 1124 | 1+YUNTRANS(y), 1+x/r, 1+y%r |
| 1125 | #endif |
| 1126 | ) || |
| 1127 | nsolve_intersect(usage, cubepos(x,y%r,n), r*cr, |
| 1128 | cubepos(0,y,n), cr*cr |
| 1129 | #ifdef STANDALONE_SOLVER |
| 1130 | , "intersectional analysis," |
| 1131 | " block (%d,%d) vs row %d", |
| 1132 | 1+x/r, 1+y%r, 1+YUNTRANS(y) |
| 1133 | #endif |
| 1134 | ))) { |
| 1135 | diff = max(diff, DIFF_INTERSECT); |
| 1136 | goto cont; |
| 1137 | } |
| 1138 | |
| 1139 | /* |
| 1140 | * Intersectional analysis, columns vs blocks. |
| 1141 | */ |
| 1142 | for (x = 0; x < cr; x++) |
| 1143 | for (y = 0; y < r; y++) |
| 1144 | for (n = 1; n <= cr; n++) |
| 1145 | if (!usage->col[x*cr+n-1] && |
| 1146 | !usage->blk[(y*c+(x/r))*cr+n-1] && |
| 1147 | (nsolve_intersect(usage, cubepos(x,0,n), cr, |
| 1148 | cubepos((x/r)*r,y,n), r*cr |
| 1149 | #ifdef STANDALONE_SOLVER |
| 1150 | , "intersectional analysis," |
| 1151 | " column %d vs block (%d,%d)", |
| 1152 | 1+x, 1+x/r, 1+y |
| 1153 | #endif |
| 1154 | ) || |
| 1155 | nsolve_intersect(usage, cubepos((x/r)*r,y,n), r*cr, |
| 1156 | cubepos(x,0,n), cr |
| 1157 | #ifdef STANDALONE_SOLVER |
| 1158 | , "intersectional analysis," |
| 1159 | " block (%d,%d) vs column %d", |
| 1160 | 1+x/r, 1+y, 1+x |
| 1161 | #endif |
| 1162 | ))) { |
| 1163 | diff = max(diff, DIFF_INTERSECT); |
| 1164 | goto cont; |
| 1165 | } |
| 1166 | |
| 1167 | /* |
| 1168 | * Blockwise set elimination. |
| 1169 | */ |
| 1170 | for (x = 0; x < cr; x += r) |
| 1171 | for (y = 0; y < r; y++) |
| 1172 | if (nsolve_set(usage, cubepos(x,y,1), r*cr, 1 |
| 1173 | #ifdef STANDALONE_SOLVER |
| 1174 | , "set elimination, block (%d,%d)", 1+x/r, 1+y |
| 1175 | #endif |
| 1176 | )) { |
| 1177 | diff = max(diff, DIFF_SET); |
| 1178 | goto cont; |
| 1179 | } |
| 1180 | |
| 1181 | /* |
| 1182 | * Row-wise set elimination. |
| 1183 | */ |
| 1184 | for (y = 0; y < cr; y++) |
| 1185 | if (nsolve_set(usage, cubepos(0,y,1), cr*cr, 1 |
| 1186 | #ifdef STANDALONE_SOLVER |
| 1187 | , "set elimination, row %d", 1+YUNTRANS(y) |
| 1188 | #endif |
| 1189 | )) { |
| 1190 | diff = max(diff, DIFF_SET); |
| 1191 | goto cont; |
| 1192 | } |
| 1193 | |
| 1194 | /* |
| 1195 | * Column-wise set elimination. |
| 1196 | */ |
| 1197 | for (x = 0; x < cr; x++) |
| 1198 | if (nsolve_set(usage, cubepos(x,0,1), cr, 1 |
| 1199 | #ifdef STANDALONE_SOLVER |
| 1200 | , "set elimination, column %d", 1+x |
| 1201 | #endif |
| 1202 | )) { |
| 1203 | diff = max(diff, DIFF_SET); |
| 1204 | goto cont; |
| 1205 | } |
| 1206 | |
| 1207 | /* |
| 1208 | * If we reach here, we have made no deductions in this |
| 1209 | * iteration, so the algorithm terminates. |
| 1210 | */ |
| 1211 | break; |
| 1212 | } |
| 1213 | |
| 1214 | sfree(usage->cube); |
| 1215 | sfree(usage->row); |
| 1216 | sfree(usage->col); |
| 1217 | sfree(usage->blk); |
| 1218 | sfree(usage); |
| 1219 | |
| 1220 | for (x = 0; x < cr; x++) |
| 1221 | for (y = 0; y < cr; y++) |
| 1222 | if (!grid[y*cr+x]) |
| 1223 | return DIFF_IMPOSSIBLE; |
| 1224 | return diff; |
| 1225 | } |
| 1226 | |
| 1227 | /* ---------------------------------------------------------------------- |
| 1228 | * End of non-recursive solver code. |
| 1229 | */ |
| 1230 | |
| 1231 | /* |
| 1232 | * Check whether a grid contains a valid complete puzzle. |
| 1233 | */ |
| 1234 | static int check_valid(int c, int r, digit *grid) |
| 1235 | { |
| 1236 | int cr = c*r; |
| 1237 | unsigned char *used; |
| 1238 | int x, y, n; |
| 1239 | |
| 1240 | used = snewn(cr, unsigned char); |
| 1241 | |
| 1242 | /* |
| 1243 | * Check that each row contains precisely one of everything. |
| 1244 | */ |
| 1245 | for (y = 0; y < cr; y++) { |
| 1246 | memset(used, FALSE, cr); |
| 1247 | for (x = 0; x < cr; x++) |
| 1248 | if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr) |
| 1249 | used[grid[y*cr+x]-1] = TRUE; |
| 1250 | for (n = 0; n < cr; n++) |
| 1251 | if (!used[n]) { |
| 1252 | sfree(used); |
| 1253 | return FALSE; |
| 1254 | } |
| 1255 | } |
| 1256 | |
| 1257 | /* |
| 1258 | * Check that each column contains precisely one of everything. |
| 1259 | */ |
| 1260 | for (x = 0; x < cr; x++) { |
| 1261 | memset(used, FALSE, cr); |
| 1262 | for (y = 0; y < cr; y++) |
| 1263 | if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr) |
| 1264 | used[grid[y*cr+x]-1] = TRUE; |
| 1265 | for (n = 0; n < cr; n++) |
| 1266 | if (!used[n]) { |
| 1267 | sfree(used); |
| 1268 | return FALSE; |
| 1269 | } |
| 1270 | } |
| 1271 | |
| 1272 | /* |
| 1273 | * Check that each block contains precisely one of everything. |
| 1274 | */ |
| 1275 | for (x = 0; x < cr; x += r) { |
| 1276 | for (y = 0; y < cr; y += c) { |
| 1277 | int xx, yy; |
| 1278 | memset(used, FALSE, cr); |
| 1279 | for (xx = x; xx < x+r; xx++) |
| 1280 | for (yy = 0; yy < y+c; yy++) |
| 1281 | if (grid[yy*cr+xx] > 0 && grid[yy*cr+xx] <= cr) |
| 1282 | used[grid[yy*cr+xx]-1] = TRUE; |
| 1283 | for (n = 0; n < cr; n++) |
| 1284 | if (!used[n]) { |
| 1285 | sfree(used); |
| 1286 | return FALSE; |
| 1287 | } |
| 1288 | } |
| 1289 | } |
| 1290 | |
| 1291 | sfree(used); |
| 1292 | return TRUE; |
| 1293 | } |
| 1294 | |
| 1295 | static void symmetry_limit(game_params *params, int *xlim, int *ylim, int s) |
| 1296 | { |
| 1297 | int c = params->c, r = params->r, cr = c*r; |
| 1298 | |
| 1299 | switch (s) { |
| 1300 | case SYMM_NONE: |
| 1301 | *xlim = *ylim = cr; |
| 1302 | break; |
| 1303 | case SYMM_ROT2: |
| 1304 | *xlim = (cr+1) / 2; |
| 1305 | *ylim = cr; |
| 1306 | break; |
| 1307 | case SYMM_REF4: |
| 1308 | case SYMM_ROT4: |
| 1309 | *xlim = *ylim = (cr+1) / 2; |
| 1310 | break; |
| 1311 | } |
| 1312 | } |
| 1313 | |
| 1314 | static int symmetries(game_params *params, int x, int y, int *output, int s) |
| 1315 | { |
| 1316 | int c = params->c, r = params->r, cr = c*r; |
| 1317 | int i = 0; |
| 1318 | |
| 1319 | *output++ = x; |
| 1320 | *output++ = y; |
| 1321 | i++; |
| 1322 | |
| 1323 | switch (s) { |
| 1324 | case SYMM_NONE: |
| 1325 | break; /* just x,y is all we need */ |
| 1326 | case SYMM_REF4: |
| 1327 | case SYMM_ROT4: |
| 1328 | switch (s) { |
| 1329 | case SYMM_REF4: |
| 1330 | *output++ = cr - 1 - x; |
| 1331 | *output++ = y; |
| 1332 | i++; |
| 1333 | |
| 1334 | *output++ = x; |
| 1335 | *output++ = cr - 1 - y; |
| 1336 | i++; |
| 1337 | break; |
| 1338 | case SYMM_ROT4: |
| 1339 | *output++ = cr - 1 - y; |
| 1340 | *output++ = x; |
| 1341 | i++; |
| 1342 | |
| 1343 | *output++ = y; |
| 1344 | *output++ = cr - 1 - x; |
| 1345 | i++; |
| 1346 | break; |
| 1347 | } |
| 1348 | /* fall through */ |
| 1349 | case SYMM_ROT2: |
| 1350 | *output++ = cr - 1 - x; |
| 1351 | *output++ = cr - 1 - y; |
| 1352 | i++; |
| 1353 | break; |
| 1354 | } |
| 1355 | |
| 1356 | return i; |
| 1357 | } |
| 1358 | |
| 1359 | struct game_aux_info { |
| 1360 | int c, r; |
| 1361 | digit *grid; |
| 1362 | }; |
| 1363 | |
| 1364 | static char *new_game_seed(game_params *params, random_state *rs, |
| 1365 | game_aux_info **aux) |
| 1366 | { |
| 1367 | int c = params->c, r = params->r, cr = c*r; |
| 1368 | int area = cr*cr; |
| 1369 | digit *grid, *grid2; |
| 1370 | struct xy { int x, y; } *locs; |
| 1371 | int nlocs; |
| 1372 | int ret; |
| 1373 | char *seed; |
| 1374 | int coords[16], ncoords; |
| 1375 | int xlim, ylim; |
| 1376 | int maxdiff, recursing; |
| 1377 | |
| 1378 | /* |
| 1379 | * Adjust the maximum difficulty level to be consistent with |
| 1380 | * the puzzle size: all 2x2 puzzles appear to be Trivial |
| 1381 | * (DIFF_BLOCK) so we cannot hold out for even a Basic |
| 1382 | * (DIFF_SIMPLE) one. |
| 1383 | */ |
| 1384 | maxdiff = params->diff; |
| 1385 | if (c == 2 && r == 2) |
| 1386 | maxdiff = DIFF_BLOCK; |
| 1387 | |
| 1388 | grid = snewn(area, digit); |
| 1389 | locs = snewn(area, struct xy); |
| 1390 | grid2 = snewn(area, digit); |
| 1391 | |
| 1392 | /* |
| 1393 | * Loop until we get a grid of the required difficulty. This is |
| 1394 | * nasty, but it seems to be unpleasantly hard to generate |
| 1395 | * difficult grids otherwise. |
| 1396 | */ |
| 1397 | do { |
| 1398 | /* |
| 1399 | * Start the recursive solver with an empty grid to generate a |
| 1400 | * random solved state. |
| 1401 | */ |
| 1402 | memset(grid, 0, area); |
| 1403 | ret = rsolve(c, r, grid, rs, 1); |
| 1404 | assert(ret == 1); |
| 1405 | assert(check_valid(c, r, grid)); |
| 1406 | |
| 1407 | /* |
| 1408 | * Save the solved grid in the aux_info. |
| 1409 | */ |
| 1410 | { |
| 1411 | game_aux_info *ai = snew(game_aux_info); |
| 1412 | ai->c = c; |
| 1413 | ai->r = r; |
| 1414 | ai->grid = snewn(cr * cr, digit); |
| 1415 | memcpy(ai->grid, grid, cr * cr * sizeof(digit)); |
| 1416 | *aux = ai; |
| 1417 | } |
| 1418 | |
| 1419 | /* |
| 1420 | * Now we have a solved grid, start removing things from it |
| 1421 | * while preserving solubility. |
| 1422 | */ |
| 1423 | symmetry_limit(params, &xlim, &ylim, params->symm); |
| 1424 | recursing = FALSE; |
| 1425 | while (1) { |
| 1426 | int x, y, i, j; |
| 1427 | |
| 1428 | /* |
| 1429 | * Iterate over the grid and enumerate all the filled |
| 1430 | * squares we could empty. |
| 1431 | */ |
| 1432 | nlocs = 0; |
| 1433 | |
| 1434 | for (x = 0; x < xlim; x++) |
| 1435 | for (y = 0; y < ylim; y++) |
| 1436 | if (grid[y*cr+x]) { |
| 1437 | locs[nlocs].x = x; |
| 1438 | locs[nlocs].y = y; |
| 1439 | nlocs++; |
| 1440 | } |
| 1441 | |
| 1442 | /* |
| 1443 | * Now shuffle that list. |
| 1444 | */ |
| 1445 | for (i = nlocs; i > 1; i--) { |
| 1446 | int p = random_upto(rs, i); |
| 1447 | if (p != i-1) { |
| 1448 | struct xy t = locs[p]; |
| 1449 | locs[p] = locs[i-1]; |
| 1450 | locs[i-1] = t; |
| 1451 | } |
| 1452 | } |
| 1453 | |
| 1454 | /* |
| 1455 | * Now loop over the shuffled list and, for each element, |
| 1456 | * see whether removing that element (and its reflections) |
| 1457 | * from the grid will still leave the grid soluble by |
| 1458 | * nsolve. |
| 1459 | */ |
| 1460 | for (i = 0; i < nlocs; i++) { |
| 1461 | int ret; |
| 1462 | |
| 1463 | x = locs[i].x; |
| 1464 | y = locs[i].y; |
| 1465 | |
| 1466 | memcpy(grid2, grid, area); |
| 1467 | ncoords = symmetries(params, x, y, coords, params->symm); |
| 1468 | for (j = 0; j < ncoords; j++) |
| 1469 | grid2[coords[2*j+1]*cr+coords[2*j]] = 0; |
| 1470 | |
| 1471 | if (recursing) |
| 1472 | ret = (rsolve(c, r, grid2, NULL, 2) == 1); |
| 1473 | else |
| 1474 | ret = (nsolve(c, r, grid2) <= maxdiff); |
| 1475 | |
| 1476 | if (ret) { |
| 1477 | for (j = 0; j < ncoords; j++) |
| 1478 | grid[coords[2*j+1]*cr+coords[2*j]] = 0; |
| 1479 | break; |
| 1480 | } |
| 1481 | } |
| 1482 | |
| 1483 | if (i == nlocs) { |
| 1484 | /* |
| 1485 | * There was nothing we could remove without |
| 1486 | * destroying solvability. If we're trying to |
| 1487 | * generate a recursion-only grid and haven't |
| 1488 | * switched over to rsolve yet, we now do; |
| 1489 | * otherwise we give up. |
| 1490 | */ |
| 1491 | if (maxdiff == DIFF_RECURSIVE && !recursing) { |
| 1492 | recursing = TRUE; |
| 1493 | } else { |
| 1494 | break; |
| 1495 | } |
| 1496 | } |
| 1497 | } |
| 1498 | |
| 1499 | memcpy(grid2, grid, area); |
| 1500 | } while (nsolve(c, r, grid2) < maxdiff); |
| 1501 | |
| 1502 | sfree(grid2); |
| 1503 | sfree(locs); |
| 1504 | |
| 1505 | /* |
| 1506 | * Now we have the grid as it will be presented to the user. |
| 1507 | * Encode it in a game seed. |
| 1508 | */ |
| 1509 | { |
| 1510 | char *p; |
| 1511 | int run, i; |
| 1512 | |
| 1513 | seed = snewn(5 * area, char); |
| 1514 | p = seed; |
| 1515 | run = 0; |
| 1516 | for (i = 0; i <= area; i++) { |
| 1517 | int n = (i < area ? grid[i] : -1); |
| 1518 | |
| 1519 | if (!n) |
| 1520 | run++; |
| 1521 | else { |
| 1522 | if (run) { |
| 1523 | while (run > 0) { |
| 1524 | int c = 'a' - 1 + run; |
| 1525 | if (run > 26) |
| 1526 | c = 'z'; |
| 1527 | *p++ = c; |
| 1528 | run -= c - ('a' - 1); |
| 1529 | } |
| 1530 | } else { |
| 1531 | /* |
| 1532 | * If there's a number in the very top left or |
| 1533 | * bottom right, there's no point putting an |
| 1534 | * unnecessary _ before or after it. |
| 1535 | */ |
| 1536 | if (p > seed && n > 0) |
| 1537 | *p++ = '_'; |
| 1538 | } |
| 1539 | if (n > 0) |
| 1540 | p += sprintf(p, "%d", n); |
| 1541 | run = 0; |
| 1542 | } |
| 1543 | } |
| 1544 | assert(p - seed < 5 * area); |
| 1545 | *p++ = '\0'; |
| 1546 | seed = sresize(seed, p - seed, char); |
| 1547 | } |
| 1548 | |
| 1549 | sfree(grid); |
| 1550 | |
| 1551 | return seed; |
| 1552 | } |
| 1553 | |
| 1554 | static void game_free_aux_info(game_aux_info *aux) |
| 1555 | { |
| 1556 | sfree(aux->grid); |
| 1557 | sfree(aux); |
| 1558 | } |
| 1559 | |
| 1560 | static char *validate_seed(game_params *params, char *seed) |
| 1561 | { |
| 1562 | int area = params->r * params->r * params->c * params->c; |
| 1563 | int squares = 0; |
| 1564 | |
| 1565 | while (*seed) { |
| 1566 | int n = *seed++; |
| 1567 | if (n >= 'a' && n <= 'z') { |
| 1568 | squares += n - 'a' + 1; |
| 1569 | } else if (n == '_') { |
| 1570 | /* do nothing */; |
| 1571 | } else if (n > '0' && n <= '9') { |
| 1572 | squares++; |
| 1573 | while (*seed >= '0' && *seed <= '9') |
| 1574 | seed++; |
| 1575 | } else |
| 1576 | return "Invalid character in game specification"; |
| 1577 | } |
| 1578 | |
| 1579 | if (squares < area) |
| 1580 | return "Not enough data to fill grid"; |
| 1581 | |
| 1582 | if (squares > area) |
| 1583 | return "Too much data to fit in grid"; |
| 1584 | |
| 1585 | return NULL; |
| 1586 | } |
| 1587 | |
| 1588 | static game_state *new_game(game_params *params, char *seed) |
| 1589 | { |
| 1590 | game_state *state = snew(game_state); |
| 1591 | int c = params->c, r = params->r, cr = c*r, area = cr * cr; |
| 1592 | int i; |
| 1593 | |
| 1594 | state->c = params->c; |
| 1595 | state->r = params->r; |
| 1596 | |
| 1597 | state->grid = snewn(area, digit); |
| 1598 | state->immutable = snewn(area, unsigned char); |
| 1599 | memset(state->immutable, FALSE, area); |
| 1600 | |
| 1601 | state->completed = state->cheated = FALSE; |
| 1602 | |
| 1603 | i = 0; |
| 1604 | while (*seed) { |
| 1605 | int n = *seed++; |
| 1606 | if (n >= 'a' && n <= 'z') { |
| 1607 | int run = n - 'a' + 1; |
| 1608 | assert(i + run <= area); |
| 1609 | while (run-- > 0) |
| 1610 | state->grid[i++] = 0; |
| 1611 | } else if (n == '_') { |
| 1612 | /* do nothing */; |
| 1613 | } else if (n > '0' && n <= '9') { |
| 1614 | assert(i < area); |
| 1615 | state->immutable[i] = TRUE; |
| 1616 | state->grid[i++] = atoi(seed-1); |
| 1617 | while (*seed >= '0' && *seed <= '9') |
| 1618 | seed++; |
| 1619 | } else { |
| 1620 | assert(!"We can't get here"); |
| 1621 | } |
| 1622 | } |
| 1623 | assert(i == area); |
| 1624 | |
| 1625 | return state; |
| 1626 | } |
| 1627 | |
| 1628 | static game_state *dup_game(game_state *state) |
| 1629 | { |
| 1630 | game_state *ret = snew(game_state); |
| 1631 | int c = state->c, r = state->r, cr = c*r, area = cr * cr; |
| 1632 | |
| 1633 | ret->c = state->c; |
| 1634 | ret->r = state->r; |
| 1635 | |
| 1636 | ret->grid = snewn(area, digit); |
| 1637 | memcpy(ret->grid, state->grid, area); |
| 1638 | |
| 1639 | ret->immutable = snewn(area, unsigned char); |
| 1640 | memcpy(ret->immutable, state->immutable, area); |
| 1641 | |
| 1642 | ret->completed = state->completed; |
| 1643 | ret->cheated = state->cheated; |
| 1644 | |
| 1645 | return ret; |
| 1646 | } |
| 1647 | |
| 1648 | static void free_game(game_state *state) |
| 1649 | { |
| 1650 | sfree(state->immutable); |
| 1651 | sfree(state->grid); |
| 1652 | sfree(state); |
| 1653 | } |
| 1654 | |
| 1655 | static game_state *solve_game(game_state *state, game_aux_info *ai, |
| 1656 | char **error) |
| 1657 | { |
| 1658 | game_state *ret; |
| 1659 | int c = state->c, r = state->r, cr = c*r; |
| 1660 | int rsolve_ret; |
| 1661 | |
| 1662 | ret = dup_game(state); |
| 1663 | ret->completed = ret->cheated = TRUE; |
| 1664 | |
| 1665 | /* |
| 1666 | * If we already have the solution in the aux_info, save |
| 1667 | * ourselves some time. |
| 1668 | */ |
| 1669 | if (ai) { |
| 1670 | |
| 1671 | assert(c == ai->c); |
| 1672 | assert(r == ai->r); |
| 1673 | memcpy(ret->grid, ai->grid, cr * cr * sizeof(digit)); |
| 1674 | |
| 1675 | } else { |
| 1676 | rsolve_ret = rsolve(c, r, ret->grid, NULL, 2); |
| 1677 | |
| 1678 | if (rsolve_ret != 1) { |
| 1679 | free_game(ret); |
| 1680 | if (rsolve_ret == 0) |
| 1681 | *error = "No solution exists for this puzzle"; |
| 1682 | else |
| 1683 | *error = "Multiple solutions exist for this puzzle"; |
| 1684 | return NULL; |
| 1685 | } |
| 1686 | } |
| 1687 | |
| 1688 | return ret; |
| 1689 | } |
| 1690 | |
| 1691 | static char *grid_text_format(int c, int r, digit *grid) |
| 1692 | { |
| 1693 | int cr = c*r; |
| 1694 | int x, y; |
| 1695 | int maxlen; |
| 1696 | char *ret, *p; |
| 1697 | |
| 1698 | /* |
| 1699 | * There are cr lines of digits, plus r-1 lines of block |
| 1700 | * separators. Each line contains cr digits, cr-1 separating |
| 1701 | * spaces, and c-1 two-character block separators. Thus, the |
| 1702 | * total length of a line is 2*cr+2*c-3 (not counting the |
| 1703 | * newline), and there are cr+r-1 of them. |
| 1704 | */ |
| 1705 | maxlen = (cr+r-1) * (2*cr+2*c-2); |
| 1706 | ret = snewn(maxlen+1, char); |
| 1707 | p = ret; |
| 1708 | |
| 1709 | for (y = 0; y < cr; y++) { |
| 1710 | for (x = 0; x < cr; x++) { |
| 1711 | int ch = grid[y * cr + x]; |
| 1712 | if (ch == 0) |
| 1713 | ch = ' '; |
| 1714 | else if (ch <= 9) |
| 1715 | ch = '0' + ch; |
| 1716 | else |
| 1717 | ch = 'a' + ch-10; |
| 1718 | *p++ = ch; |
| 1719 | if (x+1 < cr) { |
| 1720 | *p++ = ' '; |
| 1721 | if ((x+1) % r == 0) { |
| 1722 | *p++ = '|'; |
| 1723 | *p++ = ' '; |
| 1724 | } |
| 1725 | } |
| 1726 | } |
| 1727 | *p++ = '\n'; |
| 1728 | if (y+1 < cr && (y+1) % c == 0) { |
| 1729 | for (x = 0; x < cr; x++) { |
| 1730 | *p++ = '-'; |
| 1731 | if (x+1 < cr) { |
| 1732 | *p++ = '-'; |
| 1733 | if ((x+1) % r == 0) { |
| 1734 | *p++ = '+'; |
| 1735 | *p++ = '-'; |
| 1736 | } |
| 1737 | } |
| 1738 | } |
| 1739 | *p++ = '\n'; |
| 1740 | } |
| 1741 | } |
| 1742 | |
| 1743 | assert(p - ret == maxlen); |
| 1744 | *p = '\0'; |
| 1745 | return ret; |
| 1746 | } |
| 1747 | |
| 1748 | static char *game_text_format(game_state *state) |
| 1749 | { |
| 1750 | return grid_text_format(state->c, state->r, state->grid); |
| 1751 | } |
| 1752 | |
| 1753 | struct game_ui { |
| 1754 | /* |
| 1755 | * These are the coordinates of the currently highlighted |
| 1756 | * square on the grid, or -1,-1 if there isn't one. When there |
| 1757 | * is, pressing a valid number or letter key or Space will |
| 1758 | * enter that number or letter in the grid. |
| 1759 | */ |
| 1760 | int hx, hy; |
| 1761 | }; |
| 1762 | |
| 1763 | static game_ui *new_ui(game_state *state) |
| 1764 | { |
| 1765 | game_ui *ui = snew(game_ui); |
| 1766 | |
| 1767 | ui->hx = ui->hy = -1; |
| 1768 | |
| 1769 | return ui; |
| 1770 | } |
| 1771 | |
| 1772 | static void free_ui(game_ui *ui) |
| 1773 | { |
| 1774 | sfree(ui); |
| 1775 | } |
| 1776 | |
| 1777 | static game_state *make_move(game_state *from, game_ui *ui, int x, int y, |
| 1778 | int button) |
| 1779 | { |
| 1780 | int c = from->c, r = from->r, cr = c*r; |
| 1781 | int tx, ty; |
| 1782 | game_state *ret; |
| 1783 | |
| 1784 | button &= ~MOD_NUM_KEYPAD; /* we treat this the same as normal */ |
| 1785 | |
| 1786 | tx = (x + TILE_SIZE - BORDER) / TILE_SIZE - 1; |
| 1787 | ty = (y + TILE_SIZE - BORDER) / TILE_SIZE - 1; |
| 1788 | |
| 1789 | if (tx >= 0 && tx < cr && ty >= 0 && ty < cr && button == LEFT_BUTTON) { |
| 1790 | if (tx == ui->hx && ty == ui->hy) { |
| 1791 | ui->hx = ui->hy = -1; |
| 1792 | } else { |
| 1793 | ui->hx = tx; |
| 1794 | ui->hy = ty; |
| 1795 | } |
| 1796 | return from; /* UI activity occurred */ |
| 1797 | } |
| 1798 | |
| 1799 | if (ui->hx != -1 && ui->hy != -1 && |
| 1800 | ((button >= '1' && button <= '9' && button - '0' <= cr) || |
| 1801 | (button >= 'a' && button <= 'z' && button - 'a' + 10 <= cr) || |
| 1802 | (button >= 'A' && button <= 'Z' && button - 'A' + 10 <= cr) || |
| 1803 | button == ' ')) { |
| 1804 | int n = button - '0'; |
| 1805 | if (button >= 'A' && button <= 'Z') |
| 1806 | n = button - 'A' + 10; |
| 1807 | if (button >= 'a' && button <= 'z') |
| 1808 | n = button - 'a' + 10; |
| 1809 | if (button == ' ') |
| 1810 | n = 0; |
| 1811 | |
| 1812 | if (from->immutable[ui->hy*cr+ui->hx]) |
| 1813 | return NULL; /* can't overwrite this square */ |
| 1814 | |
| 1815 | ret = dup_game(from); |
| 1816 | ret->grid[ui->hy*cr+ui->hx] = n; |
| 1817 | ui->hx = ui->hy = -1; |
| 1818 | |
| 1819 | /* |
| 1820 | * We've made a real change to the grid. Check to see |
| 1821 | * if the game has been completed. |
| 1822 | */ |
| 1823 | if (!ret->completed && check_valid(c, r, ret->grid)) { |
| 1824 | ret->completed = TRUE; |
| 1825 | } |
| 1826 | |
| 1827 | return ret; /* made a valid move */ |
| 1828 | } |
| 1829 | |
| 1830 | return NULL; |
| 1831 | } |
| 1832 | |
| 1833 | /* ---------------------------------------------------------------------- |
| 1834 | * Drawing routines. |
| 1835 | */ |
| 1836 | |
| 1837 | struct game_drawstate { |
| 1838 | int started; |
| 1839 | int c, r, cr; |
| 1840 | digit *grid; |
| 1841 | unsigned char *hl; |
| 1842 | }; |
| 1843 | |
| 1844 | #define XSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1) |
| 1845 | #define YSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1) |
| 1846 | |
| 1847 | static void game_size(game_params *params, int *x, int *y) |
| 1848 | { |
| 1849 | int c = params->c, r = params->r, cr = c*r; |
| 1850 | |
| 1851 | *x = XSIZE(cr); |
| 1852 | *y = YSIZE(cr); |
| 1853 | } |
| 1854 | |
| 1855 | static float *game_colours(frontend *fe, game_state *state, int *ncolours) |
| 1856 | { |
| 1857 | float *ret = snewn(3 * NCOLOURS, float); |
| 1858 | |
| 1859 | frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]); |
| 1860 | |
| 1861 | ret[COL_GRID * 3 + 0] = 0.0F; |
| 1862 | ret[COL_GRID * 3 + 1] = 0.0F; |
| 1863 | ret[COL_GRID * 3 + 2] = 0.0F; |
| 1864 | |
| 1865 | ret[COL_CLUE * 3 + 0] = 0.0F; |
| 1866 | ret[COL_CLUE * 3 + 1] = 0.0F; |
| 1867 | ret[COL_CLUE * 3 + 2] = 0.0F; |
| 1868 | |
| 1869 | ret[COL_USER * 3 + 0] = 0.0F; |
| 1870 | ret[COL_USER * 3 + 1] = 0.6F * ret[COL_BACKGROUND * 3 + 1]; |
| 1871 | ret[COL_USER * 3 + 2] = 0.0F; |
| 1872 | |
| 1873 | ret[COL_HIGHLIGHT * 3 + 0] = 0.85F * ret[COL_BACKGROUND * 3 + 0]; |
| 1874 | ret[COL_HIGHLIGHT * 3 + 1] = 0.85F * ret[COL_BACKGROUND * 3 + 1]; |
| 1875 | ret[COL_HIGHLIGHT * 3 + 2] = 0.85F * ret[COL_BACKGROUND * 3 + 2]; |
| 1876 | |
| 1877 | *ncolours = NCOLOURS; |
| 1878 | return ret; |
| 1879 | } |
| 1880 | |
| 1881 | static game_drawstate *game_new_drawstate(game_state *state) |
| 1882 | { |
| 1883 | struct game_drawstate *ds = snew(struct game_drawstate); |
| 1884 | int c = state->c, r = state->r, cr = c*r; |
| 1885 | |
| 1886 | ds->started = FALSE; |
| 1887 | ds->c = c; |
| 1888 | ds->r = r; |
| 1889 | ds->cr = cr; |
| 1890 | ds->grid = snewn(cr*cr, digit); |
| 1891 | memset(ds->grid, 0, cr*cr); |
| 1892 | ds->hl = snewn(cr*cr, unsigned char); |
| 1893 | memset(ds->hl, 0, cr*cr); |
| 1894 | |
| 1895 | return ds; |
| 1896 | } |
| 1897 | |
| 1898 | static void game_free_drawstate(game_drawstate *ds) |
| 1899 | { |
| 1900 | sfree(ds->hl); |
| 1901 | sfree(ds->grid); |
| 1902 | sfree(ds); |
| 1903 | } |
| 1904 | |
| 1905 | static void draw_number(frontend *fe, game_drawstate *ds, game_state *state, |
| 1906 | int x, int y, int hl) |
| 1907 | { |
| 1908 | int c = state->c, r = state->r, cr = c*r; |
| 1909 | int tx, ty; |
| 1910 | int cx, cy, cw, ch; |
| 1911 | char str[2]; |
| 1912 | |
| 1913 | if (ds->grid[y*cr+x] == state->grid[y*cr+x] && ds->hl[y*cr+x] == hl) |
| 1914 | return; /* no change required */ |
| 1915 | |
| 1916 | tx = BORDER + x * TILE_SIZE + 2; |
| 1917 | ty = BORDER + y * TILE_SIZE + 2; |
| 1918 | |
| 1919 | cx = tx; |
| 1920 | cy = ty; |
| 1921 | cw = TILE_SIZE-3; |
| 1922 | ch = TILE_SIZE-3; |
| 1923 | |
| 1924 | if (x % r) |
| 1925 | cx--, cw++; |
| 1926 | if ((x+1) % r) |
| 1927 | cw++; |
| 1928 | if (y % c) |
| 1929 | cy--, ch++; |
| 1930 | if ((y+1) % c) |
| 1931 | ch++; |
| 1932 | |
| 1933 | clip(fe, cx, cy, cw, ch); |
| 1934 | |
| 1935 | /* background needs erasing? */ |
| 1936 | if (ds->grid[y*cr+x] || ds->hl[y*cr+x] != hl) |
| 1937 | draw_rect(fe, cx, cy, cw, ch, hl ? COL_HIGHLIGHT : COL_BACKGROUND); |
| 1938 | |
| 1939 | /* new number needs drawing? */ |
| 1940 | if (state->grid[y*cr+x]) { |
| 1941 | str[1] = '\0'; |
| 1942 | str[0] = state->grid[y*cr+x] + '0'; |
| 1943 | if (str[0] > '9') |
| 1944 | str[0] += 'a' - ('9'+1); |
| 1945 | draw_text(fe, tx + TILE_SIZE/2, ty + TILE_SIZE/2, |
| 1946 | FONT_VARIABLE, TILE_SIZE/2, ALIGN_VCENTRE | ALIGN_HCENTRE, |
| 1947 | state->immutable[y*cr+x] ? COL_CLUE : COL_USER, str); |
| 1948 | } |
| 1949 | |
| 1950 | unclip(fe); |
| 1951 | |
| 1952 | draw_update(fe, cx, cy, cw, ch); |
| 1953 | |
| 1954 | ds->grid[y*cr+x] = state->grid[y*cr+x]; |
| 1955 | ds->hl[y*cr+x] = hl; |
| 1956 | } |
| 1957 | |
| 1958 | static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate, |
| 1959 | game_state *state, int dir, game_ui *ui, |
| 1960 | float animtime, float flashtime) |
| 1961 | { |
| 1962 | int c = state->c, r = state->r, cr = c*r; |
| 1963 | int x, y; |
| 1964 | |
| 1965 | if (!ds->started) { |
| 1966 | /* |
| 1967 | * The initial contents of the window are not guaranteed |
| 1968 | * and can vary with front ends. To be on the safe side, |
| 1969 | * all games should start by drawing a big |
| 1970 | * background-colour rectangle covering the whole window. |
| 1971 | */ |
| 1972 | draw_rect(fe, 0, 0, XSIZE(cr), YSIZE(cr), COL_BACKGROUND); |
| 1973 | |
| 1974 | /* |
| 1975 | * Draw the grid. |
| 1976 | */ |
| 1977 | for (x = 0; x <= cr; x++) { |
| 1978 | int thick = (x % r ? 0 : 1); |
| 1979 | draw_rect(fe, BORDER + x*TILE_SIZE - thick, BORDER-1, |
| 1980 | 1+2*thick, cr*TILE_SIZE+3, COL_GRID); |
| 1981 | } |
| 1982 | for (y = 0; y <= cr; y++) { |
| 1983 | int thick = (y % c ? 0 : 1); |
| 1984 | draw_rect(fe, BORDER-1, BORDER + y*TILE_SIZE - thick, |
| 1985 | cr*TILE_SIZE+3, 1+2*thick, COL_GRID); |
| 1986 | } |
| 1987 | } |
| 1988 | |
| 1989 | /* |
| 1990 | * Draw any numbers which need redrawing. |
| 1991 | */ |
| 1992 | for (x = 0; x < cr; x++) { |
| 1993 | for (y = 0; y < cr; y++) { |
| 1994 | draw_number(fe, ds, state, x, y, |
| 1995 | (x == ui->hx && y == ui->hy) || |
| 1996 | (flashtime > 0 && |
| 1997 | (flashtime <= FLASH_TIME/3 || |
| 1998 | flashtime >= FLASH_TIME*2/3))); |
| 1999 | } |
| 2000 | } |
| 2001 | |
| 2002 | /* |
| 2003 | * Update the _entire_ grid if necessary. |
| 2004 | */ |
| 2005 | if (!ds->started) { |
| 2006 | draw_update(fe, 0, 0, XSIZE(cr), YSIZE(cr)); |
| 2007 | ds->started = TRUE; |
| 2008 | } |
| 2009 | } |
| 2010 | |
| 2011 | static float game_anim_length(game_state *oldstate, game_state *newstate, |
| 2012 | int dir) |
| 2013 | { |
| 2014 | return 0.0F; |
| 2015 | } |
| 2016 | |
| 2017 | static float game_flash_length(game_state *oldstate, game_state *newstate, |
| 2018 | int dir) |
| 2019 | { |
| 2020 | if (!oldstate->completed && newstate->completed && |
| 2021 | !oldstate->cheated && !newstate->cheated) |
| 2022 | return FLASH_TIME; |
| 2023 | return 0.0F; |
| 2024 | } |
| 2025 | |
| 2026 | static int game_wants_statusbar(void) |
| 2027 | { |
| 2028 | return FALSE; |
| 2029 | } |
| 2030 | |
| 2031 | #ifdef COMBINED |
| 2032 | #define thegame solo |
| 2033 | #endif |
| 2034 | |
| 2035 | const struct game thegame = { |
| 2036 | "Solo", "games.solo", |
| 2037 | default_params, |
| 2038 | game_fetch_preset, |
| 2039 | decode_params, |
| 2040 | encode_params, |
| 2041 | free_params, |
| 2042 | dup_params, |
| 2043 | TRUE, game_configure, custom_params, |
| 2044 | validate_params, |
| 2045 | new_game_seed, |
| 2046 | game_free_aux_info, |
| 2047 | validate_seed, |
| 2048 | new_game, |
| 2049 | dup_game, |
| 2050 | free_game, |
| 2051 | TRUE, solve_game, |
| 2052 | TRUE, game_text_format, |
| 2053 | new_ui, |
| 2054 | free_ui, |
| 2055 | make_move, |
| 2056 | game_size, |
| 2057 | game_colours, |
| 2058 | game_new_drawstate, |
| 2059 | game_free_drawstate, |
| 2060 | game_redraw, |
| 2061 | game_anim_length, |
| 2062 | game_flash_length, |
| 2063 | game_wants_statusbar, |
| 2064 | }; |
| 2065 | |
| 2066 | #ifdef STANDALONE_SOLVER |
| 2067 | |
| 2068 | /* |
| 2069 | * gcc -DSTANDALONE_SOLVER -o solosolver solo.c malloc.c |
| 2070 | */ |
| 2071 | |
| 2072 | void frontend_default_colour(frontend *fe, float *output) {} |
| 2073 | void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize, |
| 2074 | int align, int colour, char *text) {} |
| 2075 | void draw_rect(frontend *fe, int x, int y, int w, int h, int colour) {} |
| 2076 | void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour) {} |
| 2077 | void draw_polygon(frontend *fe, int *coords, int npoints, |
| 2078 | int fill, int colour) {} |
| 2079 | void clip(frontend *fe, int x, int y, int w, int h) {} |
| 2080 | void unclip(frontend *fe) {} |
| 2081 | void start_draw(frontend *fe) {} |
| 2082 | void draw_update(frontend *fe, int x, int y, int w, int h) {} |
| 2083 | void end_draw(frontend *fe) {} |
| 2084 | unsigned long random_bits(random_state *state, int bits) |
| 2085 | { assert(!"Shouldn't get randomness"); return 0; } |
| 2086 | unsigned long random_upto(random_state *state, unsigned long limit) |
| 2087 | { assert(!"Shouldn't get randomness"); return 0; } |
| 2088 | |
| 2089 | void fatal(char *fmt, ...) |
| 2090 | { |
| 2091 | va_list ap; |
| 2092 | |
| 2093 | fprintf(stderr, "fatal error: "); |
| 2094 | |
| 2095 | va_start(ap, fmt); |
| 2096 | vfprintf(stderr, fmt, ap); |
| 2097 | va_end(ap); |
| 2098 | |
| 2099 | fprintf(stderr, "\n"); |
| 2100 | exit(1); |
| 2101 | } |
| 2102 | |
| 2103 | int main(int argc, char **argv) |
| 2104 | { |
| 2105 | game_params *p; |
| 2106 | game_state *s; |
| 2107 | int recurse = TRUE; |
| 2108 | char *id = NULL, *seed, *err; |
| 2109 | int y, x; |
| 2110 | int grade = FALSE; |
| 2111 | |
| 2112 | while (--argc > 0) { |
| 2113 | char *p = *++argv; |
| 2114 | if (!strcmp(p, "-r")) { |
| 2115 | recurse = TRUE; |
| 2116 | } else if (!strcmp(p, "-n")) { |
| 2117 | recurse = FALSE; |
| 2118 | } else if (!strcmp(p, "-v")) { |
| 2119 | solver_show_working = TRUE; |
| 2120 | recurse = FALSE; |
| 2121 | } else if (!strcmp(p, "-g")) { |
| 2122 | grade = TRUE; |
| 2123 | recurse = FALSE; |
| 2124 | } else if (*p == '-') { |
| 2125 | fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0]); |
| 2126 | return 1; |
| 2127 | } else { |
| 2128 | id = p; |
| 2129 | } |
| 2130 | } |
| 2131 | |
| 2132 | if (!id) { |
| 2133 | fprintf(stderr, "usage: %s [-n | -r | -g | -v] <game_id>\n", argv[0]); |
| 2134 | return 1; |
| 2135 | } |
| 2136 | |
| 2137 | seed = strchr(id, ':'); |
| 2138 | if (!seed) { |
| 2139 | fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]); |
| 2140 | return 1; |
| 2141 | } |
| 2142 | *seed++ = '\0'; |
| 2143 | |
| 2144 | p = decode_params(id); |
| 2145 | err = validate_seed(p, seed); |
| 2146 | if (err) { |
| 2147 | fprintf(stderr, "%s: %s\n", argv[0], err); |
| 2148 | return 1; |
| 2149 | } |
| 2150 | s = new_game(p, seed); |
| 2151 | |
| 2152 | if (recurse) { |
| 2153 | int ret = rsolve(p->c, p->r, s->grid, NULL, 2); |
| 2154 | if (ret > 1) { |
| 2155 | fprintf(stderr, "%s: rsolve: multiple solutions detected\n", |
| 2156 | argv[0]); |
| 2157 | } |
| 2158 | } else { |
| 2159 | int ret = nsolve(p->c, p->r, s->grid); |
| 2160 | if (grade) { |
| 2161 | if (ret == DIFF_IMPOSSIBLE) { |
| 2162 | /* |
| 2163 | * Now resort to rsolve to determine whether it's |
| 2164 | * really soluble. |
| 2165 | */ |
| 2166 | ret = rsolve(p->c, p->r, s->grid, NULL, 2); |
| 2167 | if (ret == 0) |
| 2168 | ret = DIFF_IMPOSSIBLE; |
| 2169 | else if (ret == 1) |
| 2170 | ret = DIFF_RECURSIVE; |
| 2171 | else |
| 2172 | ret = DIFF_AMBIGUOUS; |
| 2173 | } |
| 2174 | printf("Difficulty rating: %s\n", |
| 2175 | ret==DIFF_BLOCK ? "Trivial (blockwise positional elimination only)": |
| 2176 | ret==DIFF_SIMPLE ? "Basic (row/column/number elimination required)": |
| 2177 | ret==DIFF_INTERSECT ? "Intermediate (intersectional analysis required)": |
| 2178 | ret==DIFF_SET ? "Advanced (set elimination required)": |
| 2179 | ret==DIFF_RECURSIVE ? "Unreasonable (guesswork and backtracking required)": |
| 2180 | ret==DIFF_AMBIGUOUS ? "Ambiguous (multiple solutions exist)": |
| 2181 | ret==DIFF_IMPOSSIBLE ? "Impossible (no solution exists)": |
| 2182 | "INTERNAL ERROR: unrecognised difficulty code"); |
| 2183 | } |
| 2184 | } |
| 2185 | |
| 2186 | printf("%s\n", grid_text_format(p->c, p->r, s->grid)); |
| 2187 | |
| 2188 | return 0; |
| 2189 | } |
| 2190 | |
| 2191 | #endif |