2 * solo.c: the number-placing puzzle most popularly known as `Sudoku'.
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.
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
23 * + `pencil marks' might be useful for more subtle forms of
24 * deduction, now we can create puzzles that require them.
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:
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.)
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
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.
63 #ifdef STANDALONE_SOLVER
65 int solver_show_working;
70 #define max(x,y) ((x)>(y)?(x):(y))
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.
80 typedef unsigned char digit;
86 #define FLASH_TIME 0.4F
88 enum { SYMM_NONE, SYMM_ROT2, SYMM_ROT4, SYMM_REF4 };
90 enum { DIFF_BLOCK, DIFF_SIMPLE, DIFF_INTERSECT,
91 DIFF_SET, DIFF_RECURSIVE, DIFF_AMBIGUOUS, DIFF_IMPOSSIBLE };
103 int c, r, symm, diff;
109 unsigned char *immutable; /* marks which digits are clues */
110 int completed, cheated;
113 static game_params *default_params(void)
115 game_params *ret = snew(game_params);
118 ret->symm = SYMM_ROT2; /* a plausible default */
119 ret->diff = DIFF_BLOCK; /* so is this */
124 static void free_params(game_params *params)
129 static game_params *dup_params(game_params *params)
131 game_params *ret = snew(game_params);
132 *ret = *params; /* structure copy */
136 static int game_fetch_preset(int i, char **name, game_params **params)
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 } },
153 if (i < 0 || i >= lenof(presets))
156 *name = dupstr(presets[i].title);
157 *params = dup_params(&presets[i].params);
162 static game_params *decode_params(char const *string)
164 game_params *ret = default_params();
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') {
172 ret->r = atoi(string);
173 while (*string && isdigit((unsigned char)*string)) string++;
176 if (*string == 'r' || *string == 'm' || *string == 'a') {
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;
188 ret->symm = SYMM_NONE;
189 } else if (*string == 'd') {
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;
202 string++; /* eat unknown character */
208 static char *encode_params(game_params *params)
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
217 sprintf(str, "%dx%d", params->c, params->r);
221 static config_item *game_configure(game_params *params)
226 ret = snewn(5, config_item);
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);
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);
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;
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;
258 static game_params *custom_params(config_item *cfg)
260 game_params *ret = snew(game_params);
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;
270 static char *validate_params(game_params *params)
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";
279 /* ----------------------------------------------------------------------
280 * Full recursive Solo solver.
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.
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.
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
308 * Internal data structure used in solver to keep track of
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 */
316 /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
318 /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
320 /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
322 /* This lists all the empty spaces remaining in the grid. */
323 struct rsolve_coord *spaces;
325 /* If we need randomisation in the solve, this is our random state. */
327 /* Number of solutions so far found, and maximum number we care about. */
332 * The real recursive step in the solving function.
334 static void rsolve_real(struct rsolve_usage *usage, digit *grid)
336 int c = usage->c, r = usage->r, cr = usage->cr;
337 int i, j, n, sx, sy, bestm, bestr;
341 * Firstly, check for completion! If there are no spaces left
342 * in the grid, we have a solution.
344 if (usage->nspaces == 0) {
347 * This is our first solution, so fill in the output grid.
349 memcpy(grid, usage->grid, cr * cr);
356 * Otherwise, there must be at least one space. Find the most
357 * constrained space, using the `r' field as a tie-breaker.
359 bestm = cr+1; /* so that any space will beat it */
362 for (j = 0; j < usage->nspaces; j++) {
363 int x = usage->spaces[j].x, y = usage->spaces[j].y;
367 * Find the number of digits that could go in this space.
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])
375 if (m < bestm || (m == bestm && usage->spaces[j].r < bestr)) {
377 bestr = usage->spaces[j].r;
385 * Swap that square into the final place in the spaces array,
386 * so that decrementing nspaces will remove it from the list.
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;
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.
400 digits = snewn(bestm, int);
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]) {
410 for (i = j; i > 1; i--) {
411 int p = random_upto(usage->rs, i);
414 digits[p] = digits[i-1];
420 /* And finally, go through the digit list and actually recurse. */
421 for (i = 0; i < j; i++) {
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;
430 /* Call the solver recursively. */
431 rsolve_real(usage, grid);
434 * If we have seen as many solutions as we need, terminate
435 * all processing immediately.
437 if (usage->solns >= usage->maxsolns)
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;
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.
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
463 static int rsolve(int c, int r, digit *grid, random_state *rs, int max)
465 struct rsolve_usage *usage;
470 * Create an rsolve_usage structure.
472 usage = snew(struct rsolve_usage);
478 usage->grid = snewn(cr * cr, digit);
479 memcpy(usage->grid, grid, cr * cr);
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);
488 usage->spaces = snewn(cr * cr, struct rsolve_coord);
492 usage->maxsolns = max;
497 * Now fill it in with data from the input grid.
499 for (y = 0; y < cr; y++) {
500 for (x = 0; x < cr; x++) {
501 int v = grid[y*cr+x];
503 usage->spaces[usage->nspaces].x = x;
504 usage->spaces[usage->nspaces].y = y;
506 usage->spaces[usage->nspaces].r = random_bits(rs, 31);
508 usage->spaces[usage->nspaces].r = usage->nspaces;
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;
519 * Run the real recursive solving function.
521 rsolve_real(usage, grid);
525 * Clean up the usage structure now we have our answer.
527 sfree(usage->spaces);
540 /* ----------------------------------------------------------------------
541 * End of recursive solver code.
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).
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.
556 * Modes of reasoning currently supported:
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.
562 * - Numeric elimination: a square must have a particular number
563 * in because all the other numbers that could go in it are
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.
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
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,
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.
610 #define YTRANS(y) (((y)%c)*r+(y)/c)
611 #define YUNTRANS(y) (((y)%r)*c+(y)/r)
613 struct nsolve_usage {
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.
620 * The way to index this array is cube[(x*cr+y)*cr+n-1].
621 * y-coordinates in here are transformed.
625 * This is the grid in which we write down our final
626 * deductions. y-coordinates in here are _not_ transformed.
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
634 /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
636 /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
638 /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
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)])
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
649 static void nsolve_place(struct nsolve_usage *usage, int x, int y, int n)
651 int c = usage->c, r = usage->r, cr = usage->cr;
657 * Rule out all other numbers in this square.
659 for (i = 1; i <= cr; i++)
664 * Rule out this number in all other positions in the row.
666 for (i = 0; i < cr; i++)
671 * Rule out this number in all other positions in the column.
673 for (i = 0; i < cr; i++)
678 * Rule out this number in all other positions in the block.
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;
688 * Enter the number in the result grid.
690 usage->grid[YUNTRANS(y)*cr+x] = n;
693 * Cross out this number from the list of numbers left to place
694 * in its row, its column and its block.
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;
700 static int nsolve_elim(struct nsolve_usage *usage, int start, int step
701 #ifdef STANDALONE_SOLVER
706 int c = usage->c, r = usage->r, cr = c*r;
710 * Count the number of set bits within this section of the
715 for (i = 0; i < cr; i++)
716 if (usage->cube[start+i*step]) {
730 if (!usage->grid[YUNTRANS(y)*cr+x]) {
731 #ifdef STANDALONE_SOLVER
732 if (solver_show_working) {
737 printf(":\n placing %d at (%d,%d)\n",
738 n, 1+x, 1+YUNTRANS(y));
741 nsolve_place(usage, x, y, n);
749 static int nsolve_intersect(struct nsolve_usage *usage,
750 int start1, int step1, int start2, int step2
751 #ifdef STANDALONE_SOLVER
756 int c = usage->c, r = usage->r, cr = c*r;
760 * Loop over the first domain and see if there's any set bit
761 * not also in the second.
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 */
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.
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))
783 #ifdef STANDALONE_SOLVER
784 if (solver_show_working) {
800 printf(" ruling out %d at (%d,%d)\n",
801 pn, 1+px, 1+YUNTRANS(py));
804 ret = TRUE; /* we did something */
812 static int nsolve_set(struct nsolve_usage *usage,
813 int start, int step1, int step2
814 #ifdef STANDALONE_SOLVER
819 int c = usage->c, r = usage->r, cr = c*r;
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);
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.
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])
841 * This condition actually marks a completely insoluble
842 * (i.e. internally inconsistent) puzzle. We return and
843 * report no progress made.
848 rowidx[i] = colidx[first] = FALSE;
852 * Convert each of rowidx/colidx from a list of 0s and 1s to a
853 * list of the indices of the 1s.
855 for (i = j = 0; i < cr; i++)
859 for (i = j = 0; i < cr; i++)
865 * And create the smaller matrix.
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];
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.
883 * We have a candidate set. If its size is <=1 or >=n-1
884 * then we move on immediately.
886 if (count > 1 && count < n-1) {
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'.
893 for (i = 0; i < n; i++) {
895 for (j = 0; j < n; j++)
896 if (set[j] && grid[i*cr+j]) {
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
912 assert(rows <= n - count);
913 if (rows >= n - count) {
914 int progress = FALSE;
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.
923 * This involves referring back through
924 * rowidx/colidx in order to work out which actual
925 * positions in the cube to meddle with.
927 for (i = 0; i < n; i++) {
929 for (j = 0; j < n; j++)
930 if (set[j] && grid[i*cr+j]) {
935 for (j = 0; j < n; j++)
936 if (!set[j] && grid[i*cr+j]) {
937 int fpos = (start+rowidx[i]*step1+
939 #ifdef STANDALONE_SOLVER
940 if (solver_show_working) {
956 printf(" ruling out %d at (%d,%d)\n",
957 pn, 1+px, 1+YUNTRANS(py));
961 usage->cube[fpos] = FALSE;
977 * Binary increment: change the rightmost 0 to a 1, and
978 * change all 1s to the right of it to 0s.
981 while (i > 0 && set[i-1])
982 set[--i] = 0, count--;
984 set[--i] = 1, count++;
997 static int nsolve(int c, int r, digit *grid)
999 struct nsolve_usage *usage;
1002 int diff = DIFF_BLOCK;
1005 * Set up a usage structure as a clean slate (everything
1008 usage = snew(struct nsolve_usage);
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);
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);
1024 * Place all the clue numbers we are given.
1026 for (x = 0; x < cr; x++)
1027 for (y = 0; y < cr; y++)
1029 nsolve_place(usage, x, YTRANS(y), grid[y*cr+x]);
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
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.
1049 * Blockwise positional elimination.
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
1061 diff = max(diff, DIFF_BLOCK);
1066 * Row-wise positional elimination.
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)
1077 diff = max(diff, DIFF_SIMPLE);
1081 * Column-wise positional elimination.
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
1091 diff = max(diff, DIFF_SIMPLE);
1096 * Numeric elimination.
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,
1107 diff = max(diff, DIFF_SIMPLE);
1112 * Intersectional analysis, rows vs blocks.
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
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)
1135 diff = max(diff, DIFF_INTERSECT);
1140 * Intersectional analysis, columns vs blocks.
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)",
1155 nsolve_intersect(usage, cubepos((x/r)*r,y,n), r*cr,
1157 #ifdef STANDALONE_SOLVER
1158 , "intersectional analysis,"
1159 " block (%d,%d) vs column %d",
1163 diff = max(diff, DIFF_INTERSECT);
1168 * Blockwise set elimination.
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
1177 diff = max(diff, DIFF_SET);
1182 * Row-wise set elimination.
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)
1190 diff = max(diff, DIFF_SET);
1195 * Column-wise set elimination.
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
1203 diff = max(diff, DIFF_SET);
1208 * If we reach here, we have made no deductions in this
1209 * iteration, so the algorithm terminates.
1220 for (x = 0; x < cr; x++)
1221 for (y = 0; y < cr; y++)
1223 return DIFF_IMPOSSIBLE;
1227 /* ----------------------------------------------------------------------
1228 * End of non-recursive solver code.
1232 * Check whether a grid contains a valid complete puzzle.
1234 static int check_valid(int c, int r, digit *grid)
1237 unsigned char *used;
1240 used = snewn(cr, unsigned char);
1243 * Check that each row contains precisely one of everything.
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++)
1258 * Check that each column contains precisely one of everything.
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++)
1273 * Check that each block contains precisely one of everything.
1275 for (x = 0; x < cr; x += r) {
1276 for (y = 0; y < cr; y += c) {
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++)
1295 static void symmetry_limit(game_params *params, int *xlim, int *ylim, int s)
1297 int c = params->c, r = params->r, cr = c*r;
1309 *xlim = *ylim = (cr+1) / 2;
1314 static int symmetries(game_params *params, int x, int y, int *output, int s)
1316 int c = params->c, r = params->r, cr = c*r;
1325 break; /* just x,y is all we need */
1330 *output++ = cr - 1 - x;
1335 *output++ = cr - 1 - y;
1339 *output++ = cr - 1 - y;
1344 *output++ = cr - 1 - x;
1350 *output++ = cr - 1 - x;
1351 *output++ = cr - 1 - y;
1359 struct game_aux_info {
1364 static char *new_game_seed(game_params *params, random_state *rs,
1365 game_aux_info **aux)
1367 int c = params->c, r = params->r, cr = c*r;
1369 digit *grid, *grid2;
1370 struct xy { int x, y; } *locs;
1374 int coords[16], ncoords;
1376 int maxdiff, recursing;
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.
1384 maxdiff = params->diff;
1385 if (c == 2 && r == 2)
1386 maxdiff = DIFF_BLOCK;
1388 grid = snewn(area, digit);
1389 locs = snewn(area, struct xy);
1390 grid2 = snewn(area, digit);
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.
1399 * Start the recursive solver with an empty grid to generate a
1400 * random solved state.
1402 memset(grid, 0, area);
1403 ret = rsolve(c, r, grid, rs, 1);
1405 assert(check_valid(c, r, grid));
1408 * Save the solved grid in the aux_info.
1411 game_aux_info *ai = snew(game_aux_info);
1414 ai->grid = snewn(cr * cr, digit);
1415 memcpy(ai->grid, grid, cr * cr * sizeof(digit));
1420 * Now we have a solved grid, start removing things from it
1421 * while preserving solubility.
1423 symmetry_limit(params, &xlim, &ylim, params->symm);
1429 * Iterate over the grid and enumerate all the filled
1430 * squares we could empty.
1434 for (x = 0; x < xlim; x++)
1435 for (y = 0; y < ylim; y++)
1443 * Now shuffle that list.
1445 for (i = nlocs; i > 1; i--) {
1446 int p = random_upto(rs, i);
1448 struct xy t = locs[p];
1449 locs[p] = locs[i-1];
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
1460 for (i = 0; i < nlocs; i++) {
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;
1472 ret = (rsolve(c, r, grid2, NULL, 2) == 1);
1474 ret = (nsolve(c, r, grid2) <= maxdiff);
1477 for (j = 0; j < ncoords; j++)
1478 grid[coords[2*j+1]*cr+coords[2*j]] = 0;
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.
1491 if (maxdiff == DIFF_RECURSIVE && !recursing) {
1499 memcpy(grid2, grid, area);
1500 } while (nsolve(c, r, grid2) < maxdiff);
1506 * Now we have the grid as it will be presented to the user.
1507 * Encode it in a game seed.
1513 seed = snewn(5 * area, char);
1516 for (i = 0; i <= area; i++) {
1517 int n = (i < area ? grid[i] : -1);
1524 int c = 'a' - 1 + run;
1528 run -= c - ('a' - 1);
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.
1536 if (p > seed && n > 0)
1540 p += sprintf(p, "%d", n);
1544 assert(p - seed < 5 * area);
1546 seed = sresize(seed, p - seed, char);
1554 static void game_free_aux_info(game_aux_info *aux)
1560 static char *validate_seed(game_params *params, char *seed)
1562 int area = params->r * params->r * params->c * params->c;
1567 if (n >= 'a' && n <= 'z') {
1568 squares += n - 'a' + 1;
1569 } else if (n == '_') {
1571 } else if (n > '0' && n <= '9') {
1573 while (*seed >= '0' && *seed <= '9')
1576 return "Invalid character in game specification";
1580 return "Not enough data to fill grid";
1583 return "Too much data to fit in grid";
1588 static game_state *new_game(game_params *params, char *seed)
1590 game_state *state = snew(game_state);
1591 int c = params->c, r = params->r, cr = c*r, area = cr * cr;
1594 state->c = params->c;
1595 state->r = params->r;
1597 state->grid = snewn(area, digit);
1598 state->immutable = snewn(area, unsigned char);
1599 memset(state->immutable, FALSE, area);
1601 state->completed = state->cheated = FALSE;
1606 if (n >= 'a' && n <= 'z') {
1607 int run = n - 'a' + 1;
1608 assert(i + run <= area);
1610 state->grid[i++] = 0;
1611 } else if (n == '_') {
1613 } else if (n > '0' && n <= '9') {
1615 state->immutable[i] = TRUE;
1616 state->grid[i++] = atoi(seed-1);
1617 while (*seed >= '0' && *seed <= '9')
1620 assert(!"We can't get here");
1628 static game_state *dup_game(game_state *state)
1630 game_state *ret = snew(game_state);
1631 int c = state->c, r = state->r, cr = c*r, area = cr * cr;
1636 ret->grid = snewn(area, digit);
1637 memcpy(ret->grid, state->grid, area);
1639 ret->immutable = snewn(area, unsigned char);
1640 memcpy(ret->immutable, state->immutable, area);
1642 ret->completed = state->completed;
1643 ret->cheated = state->cheated;
1648 static void free_game(game_state *state)
1650 sfree(state->immutable);
1655 static game_state *solve_game(game_state *state, game_aux_info *ai,
1659 int c = state->c, r = state->r, cr = c*r;
1662 ret = dup_game(state);
1663 ret->completed = ret->cheated = TRUE;
1666 * If we already have the solution in the aux_info, save
1667 * ourselves some time.
1673 memcpy(ret->grid, ai->grid, cr * cr * sizeof(digit));
1676 rsolve_ret = rsolve(c, r, ret->grid, NULL, 2);
1678 if (rsolve_ret != 1) {
1680 if (rsolve_ret == 0)
1681 *error = "No solution exists for this puzzle";
1683 *error = "Multiple solutions exist for this puzzle";
1691 static char *grid_text_format(int c, int r, digit *grid)
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.
1705 maxlen = (cr+r-1) * (2*cr+2*c-2);
1706 ret = snewn(maxlen+1, char);
1709 for (y = 0; y < cr; y++) {
1710 for (x = 0; x < cr; x++) {
1711 int ch = grid[y * cr + x];
1721 if ((x+1) % r == 0) {
1728 if (y+1 < cr && (y+1) % c == 0) {
1729 for (x = 0; x < cr; x++) {
1733 if ((x+1) % r == 0) {
1743 assert(p - ret == maxlen);
1748 static char *game_text_format(game_state *state)
1750 return grid_text_format(state->c, state->r, state->grid);
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.
1763 static game_ui *new_ui(game_state *state)
1765 game_ui *ui = snew(game_ui);
1767 ui->hx = ui->hy = -1;
1772 static void free_ui(game_ui *ui)
1777 static game_state *make_move(game_state *from, game_ui *ui, int x, int y,
1780 int c = from->c, r = from->r, cr = c*r;
1784 button &= ~MOD_NUM_KEYPAD; /* we treat this the same as normal */
1786 tx = (x + TILE_SIZE - BORDER) / TILE_SIZE - 1;
1787 ty = (y + TILE_SIZE - BORDER) / TILE_SIZE - 1;
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;
1796 return from; /* UI activity occurred */
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) ||
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;
1812 if (from->immutable[ui->hy*cr+ui->hx])
1813 return NULL; /* can't overwrite this square */
1815 ret = dup_game(from);
1816 ret->grid[ui->hy*cr+ui->hx] = n;
1817 ui->hx = ui->hy = -1;
1820 * We've made a real change to the grid. Check to see
1821 * if the game has been completed.
1823 if (!ret->completed && check_valid(c, r, ret->grid)) {
1824 ret->completed = TRUE;
1827 return ret; /* made a valid move */
1833 /* ----------------------------------------------------------------------
1837 struct game_drawstate {
1844 #define XSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
1845 #define YSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
1847 static void game_size(game_params *params, int *x, int *y)
1849 int c = params->c, r = params->r, cr = c*r;
1855 static float *game_colours(frontend *fe, game_state *state, int *ncolours)
1857 float *ret = snewn(3 * NCOLOURS, float);
1859 frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
1861 ret[COL_GRID * 3 + 0] = 0.0F;
1862 ret[COL_GRID * 3 + 1] = 0.0F;
1863 ret[COL_GRID * 3 + 2] = 0.0F;
1865 ret[COL_CLUE * 3 + 0] = 0.0F;
1866 ret[COL_CLUE * 3 + 1] = 0.0F;
1867 ret[COL_CLUE * 3 + 2] = 0.0F;
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;
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];
1877 *ncolours = NCOLOURS;
1881 static game_drawstate *game_new_drawstate(game_state *state)
1883 struct game_drawstate *ds = snew(struct game_drawstate);
1884 int c = state->c, r = state->r, cr = c*r;
1886 ds->started = FALSE;
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);
1898 static void game_free_drawstate(game_drawstate *ds)
1905 static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
1906 int x, int y, int hl)
1908 int c = state->c, r = state->r, cr = c*r;
1913 if (ds->grid[y*cr+x] == state->grid[y*cr+x] && ds->hl[y*cr+x] == hl)
1914 return; /* no change required */
1916 tx = BORDER + x * TILE_SIZE + 2;
1917 ty = BORDER + y * TILE_SIZE + 2;
1933 clip(fe, cx, cy, cw, ch);
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);
1939 /* new number needs drawing? */
1940 if (state->grid[y*cr+x]) {
1942 str[0] = state->grid[y*cr+x] + '0';
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);
1952 draw_update(fe, cx, cy, cw, ch);
1954 ds->grid[y*cr+x] = state->grid[y*cr+x];
1955 ds->hl[y*cr+x] = hl;
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)
1962 int c = state->c, r = state->r, cr = c*r;
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.
1972 draw_rect(fe, 0, 0, XSIZE(cr), YSIZE(cr), COL_BACKGROUND);
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);
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);
1990 * Draw any numbers which need redrawing.
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) ||
1997 (flashtime <= FLASH_TIME/3 ||
1998 flashtime >= FLASH_TIME*2/3)));
2003 * Update the _entire_ grid if necessary.
2006 draw_update(fe, 0, 0, XSIZE(cr), YSIZE(cr));
2011 static float game_anim_length(game_state *oldstate, game_state *newstate,
2017 static float game_flash_length(game_state *oldstate, game_state *newstate,
2020 if (!oldstate->completed && newstate->completed &&
2021 !oldstate->cheated && !newstate->cheated)
2026 static int game_wants_statusbar(void)
2032 #define thegame solo
2035 const struct game thegame = {
2036 "Solo", "games.solo",
2043 TRUE, game_configure, custom_params,
2052 TRUE, game_text_format,
2059 game_free_drawstate,
2063 game_wants_statusbar,
2066 #ifdef STANDALONE_SOLVER
2069 * gcc -DSTANDALONE_SOLVER -o solosolver solo.c malloc.c
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; }
2089 void fatal(char *fmt, ...)
2093 fprintf(stderr, "fatal error: ");
2096 vfprintf(stderr, fmt, ap);
2099 fprintf(stderr, "\n");
2103 int main(int argc, char **argv)
2108 char *id = NULL, *seed, *err;
2112 while (--argc > 0) {
2114 if (!strcmp(p, "-r")) {
2116 } else if (!strcmp(p, "-n")) {
2118 } else if (!strcmp(p, "-v")) {
2119 solver_show_working = TRUE;
2121 } else if (!strcmp(p, "-g")) {
2124 } else if (*p == '-') {
2125 fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0]);
2133 fprintf(stderr, "usage: %s [-n | -r | -g | -v] <game_id>\n", argv[0]);
2137 seed = strchr(id, ':');
2139 fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]);
2144 p = decode_params(id);
2145 err = validate_seed(p, seed);
2147 fprintf(stderr, "%s: %s\n", argv[0], err);
2150 s = new_game(p, seed);
2153 int ret = rsolve(p->c, p->r, s->grid, NULL, 2);
2155 fprintf(stderr, "%s: rsolve: multiple solutions detected\n",
2159 int ret = nsolve(p->c, p->r, s->grid);
2161 if (ret == DIFF_IMPOSSIBLE) {
2163 * Now resort to rsolve to determine whether it's
2166 ret = rsolve(p->c, p->r, s->grid, NULL, 2);
2168 ret = DIFF_IMPOSSIBLE;
2170 ret = DIFF_RECURSIVE;
2172 ret = DIFF_AMBIGUOUS;
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");
2186 printf("%s\n", grid_text_format(p->c, p->r, s->grid));