2 * solo.c: the number-placing puzzle most popularly known as `Sudoku'.
6 * - reports from users are that `Trivial'-mode puzzles are still
7 * rather hard compared to newspapers' easy ones, so some better
8 * low-end difficulty grading would be nice
9 * + it's possible that really easy puzzles always have
10 * _several_ things you can do, so don't make you hunt too
11 * hard for the one deduction you can currently make
12 * + it's also possible that easy puzzles require fewer
13 * cross-eliminations: perhaps there's a higher incidence of
14 * things you can deduce by looking only at (say) rows,
15 * rather than things you have to check both rows and columns
17 * + but really, what I need to do is find some really easy
18 * puzzles and _play_ them, to see what's actually easy about
20 * + while I'm revamping this area, filling in the _last_
21 * number in a nearly-full row or column should certainly be
22 * permitted even at the lowest difficulty level.
23 * + also Owen noticed that `Basic' grids requiring numeric
24 * elimination are actually very hard, so I wonder if a
25 * difficulty gradation between that and positional-
26 * elimination-only might be in order
27 * + but it's not good to have _too_ many difficulty levels, or
28 * it'll take too long to randomly generate a given level.
30 * - it might still be nice to do some prioritisation on the
31 * removal of numbers from the grid
32 * + one possibility is to try to minimise the maximum number
33 * of filled squares in any block, which in particular ought
34 * to enforce never leaving a completely filled block in the
35 * puzzle as presented.
37 * - alternative interface modes
38 * + sudoku.com's Windows program has a palette of possible
39 * entries; you select a palette entry first and then click
40 * on the square you want it to go in, thus enabling
41 * mouse-only play. Useful for PDAs! I don't think it's
42 * actually incompatible with the current highlight-then-type
43 * approach: you _either_ highlight a palette entry and then
44 * click, _or_ you highlight a square and then type. At most
45 * one thing is ever highlighted at a time, so there's no way
47 * + then again, I don't actually like sudoku.com's interface;
48 * it's too much like a paint package whereas I prefer to
49 * think of Solo as a text editor.
50 * + another PDA-friendly possibility is a drag interface:
51 * _drag_ numbers from the palette into the grid squares.
52 * Thought experiments suggest I'd prefer that to the
53 * sudoku.com approach, but I haven't actually tried it.
57 * Solo puzzles need to be square overall (since each row and each
58 * column must contain one of every digit), but they need not be
59 * subdivided the same way internally. I am going to adopt a
60 * convention whereby I _always_ refer to `r' as the number of rows
61 * of _big_ divisions, and `c' as the number of columns of _big_
62 * divisions. Thus, a 2c by 3r puzzle looks something like this:
66 * ------+------ (Of course, you can't subdivide it the other way
67 * 1 4 5 | 6 3 2 or you'll get clashes; observe that the 4 in the
68 * 3 2 6 | 4 1 5 top left would conflict with the 4 in the second
69 * ------+------ box down on the left-hand side.)
73 * The need for a strong naming convention should now be clear:
74 * each small box is two rows of digits by three columns, while the
75 * overall puzzle has three rows of small boxes by two columns. So
76 * I will (hopefully) consistently use `r' to denote the number of
77 * rows _of small boxes_ (here 3), which is also the number of
78 * columns of digits in each small box; and `c' vice versa (here
81 * I'm also going to choose arbitrarily to list c first wherever
82 * possible: the above is a 2x3 puzzle, not a 3x2 one.
92 #ifdef STANDALONE_SOLVER
94 int solver_show_working;
100 * To save space, I store digits internally as unsigned char. This
101 * imposes a hard limit of 255 on the order of the puzzle. Since
102 * even a 5x5 takes unacceptably long to generate, I don't see this
103 * as a serious limitation unless something _really_ impressive
104 * happens in computing technology; but here's a typedef anyway for
105 * general good practice.
107 typedef unsigned char digit;
108 #define ORDER_MAX 255
113 #define FLASH_TIME 0.4F
115 enum { SYMM_NONE, SYMM_ROT2, SYMM_ROT4, SYMM_REF4 };
117 enum { DIFF_BLOCK, DIFF_SIMPLE, DIFF_INTERSECT,
118 DIFF_SET, DIFF_RECURSIVE, DIFF_AMBIGUOUS, DIFF_IMPOSSIBLE };
132 int c, r, symm, diff;
138 unsigned char *pencil; /* c*r*c*r elements */
139 unsigned char *immutable; /* marks which digits are clues */
140 int completed, cheated;
143 static game_params *default_params(void)
145 game_params *ret = snew(game_params);
148 ret->symm = SYMM_ROT2; /* a plausible default */
149 ret->diff = DIFF_BLOCK; /* so is this */
154 static void free_params(game_params *params)
159 static game_params *dup_params(game_params *params)
161 game_params *ret = snew(game_params);
162 *ret = *params; /* structure copy */
166 static int game_fetch_preset(int i, char **name, game_params **params)
172 { "2x2 Trivial", { 2, 2, SYMM_ROT2, DIFF_BLOCK } },
173 { "2x3 Basic", { 2, 3, SYMM_ROT2, DIFF_SIMPLE } },
174 { "3x3 Trivial", { 3, 3, SYMM_ROT2, DIFF_BLOCK } },
175 { "3x3 Basic", { 3, 3, SYMM_ROT2, DIFF_SIMPLE } },
176 { "3x3 Intermediate", { 3, 3, SYMM_ROT2, DIFF_INTERSECT } },
177 { "3x3 Advanced", { 3, 3, SYMM_ROT2, DIFF_SET } },
178 { "3x3 Unreasonable", { 3, 3, SYMM_ROT2, DIFF_RECURSIVE } },
180 { "3x4 Basic", { 3, 4, SYMM_ROT2, DIFF_SIMPLE } },
181 { "4x4 Basic", { 4, 4, SYMM_ROT2, DIFF_SIMPLE } },
185 if (i < 0 || i >= lenof(presets))
188 *name = dupstr(presets[i].title);
189 *params = dup_params(&presets[i].params);
194 static void decode_params(game_params *ret, char const *string)
196 ret->c = ret->r = atoi(string);
197 while (*string && isdigit((unsigned char)*string)) string++;
198 if (*string == 'x') {
200 ret->r = atoi(string);
201 while (*string && isdigit((unsigned char)*string)) string++;
204 if (*string == 'r' || *string == 'm' || *string == 'a') {
208 while (*string && isdigit((unsigned char)*string)) string++;
209 if (sc == 'm' && sn == 4)
210 ret->symm = SYMM_REF4;
211 if (sc == 'r' && sn == 4)
212 ret->symm = SYMM_ROT4;
213 if (sc == 'r' && sn == 2)
214 ret->symm = SYMM_ROT2;
216 ret->symm = SYMM_NONE;
217 } else if (*string == 'd') {
219 if (*string == 't') /* trivial */
220 string++, ret->diff = DIFF_BLOCK;
221 else if (*string == 'b') /* basic */
222 string++, ret->diff = DIFF_SIMPLE;
223 else if (*string == 'i') /* intermediate */
224 string++, ret->diff = DIFF_INTERSECT;
225 else if (*string == 'a') /* advanced */
226 string++, ret->diff = DIFF_SET;
227 else if (*string == 'u') /* unreasonable */
228 string++, ret->diff = DIFF_RECURSIVE;
230 string++; /* eat unknown character */
234 static char *encode_params(game_params *params, int full)
238 sprintf(str, "%dx%d", params->c, params->r);
240 switch (params->symm) {
241 case SYMM_REF4: strcat(str, "m4"); break;
242 case SYMM_ROT4: strcat(str, "r4"); break;
243 /* case SYMM_ROT2: strcat(str, "r2"); break; [default] */
244 case SYMM_NONE: strcat(str, "a"); break;
246 switch (params->diff) {
247 /* case DIFF_BLOCK: strcat(str, "dt"); break; [default] */
248 case DIFF_SIMPLE: strcat(str, "db"); break;
249 case DIFF_INTERSECT: strcat(str, "di"); break;
250 case DIFF_SET: strcat(str, "da"); break;
251 case DIFF_RECURSIVE: strcat(str, "du"); break;
257 static config_item *game_configure(game_params *params)
262 ret = snewn(5, config_item);
264 ret[0].name = "Columns of sub-blocks";
265 ret[0].type = C_STRING;
266 sprintf(buf, "%d", params->c);
267 ret[0].sval = dupstr(buf);
270 ret[1].name = "Rows of sub-blocks";
271 ret[1].type = C_STRING;
272 sprintf(buf, "%d", params->r);
273 ret[1].sval = dupstr(buf);
276 ret[2].name = "Symmetry";
277 ret[2].type = C_CHOICES;
278 ret[2].sval = ":None:2-way rotation:4-way rotation:4-way mirror";
279 ret[2].ival = params->symm;
281 ret[3].name = "Difficulty";
282 ret[3].type = C_CHOICES;
283 ret[3].sval = ":Trivial:Basic:Intermediate:Advanced:Unreasonable";
284 ret[3].ival = params->diff;
294 static game_params *custom_params(config_item *cfg)
296 game_params *ret = snew(game_params);
298 ret->c = atoi(cfg[0].sval);
299 ret->r = atoi(cfg[1].sval);
300 ret->symm = cfg[2].ival;
301 ret->diff = cfg[3].ival;
306 static char *validate_params(game_params *params)
308 if (params->c < 2 || params->r < 2)
309 return "Both dimensions must be at least 2";
310 if (params->c > ORDER_MAX || params->r > ORDER_MAX)
311 return "Dimensions greater than "STR(ORDER_MAX)" are not supported";
315 /* ----------------------------------------------------------------------
316 * Full recursive Solo solver.
318 * The algorithm for this solver is shamelessly copied from a
319 * Python solver written by Andrew Wilkinson (which is GPLed, but
320 * I've reused only ideas and no code). It mostly just does the
321 * obvious recursive thing: pick an empty square, put one of the
322 * possible digits in it, recurse until all squares are filled,
323 * backtrack and change some choices if necessary.
325 * The clever bit is that every time it chooses which square to
326 * fill in next, it does so by counting the number of _possible_
327 * numbers that can go in each square, and it prioritises so that
328 * it picks a square with the _lowest_ number of possibilities. The
329 * idea is that filling in lots of the obvious bits (particularly
330 * any squares with only one possibility) will cut down on the list
331 * of possibilities for other squares and hence reduce the enormous
332 * search space as much as possible as early as possible.
334 * In practice the algorithm appeared to work very well; run on
335 * sample problems from the Times it completed in well under a
336 * second on my G5 even when written in Python, and given an empty
337 * grid (so that in principle it would enumerate _all_ solved
338 * grids!) it found the first valid solution just as quickly. So
339 * with a bit more randomisation I see no reason not to use this as
344 * Internal data structure used in solver to keep track of
347 struct rsolve_coord { int x, y, r; };
348 struct rsolve_usage {
349 int c, r, cr; /* cr == c*r */
350 /* grid is a copy of the input grid, modified as we go along */
352 /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
354 /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
356 /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
358 /* This lists all the empty spaces remaining in the grid. */
359 struct rsolve_coord *spaces;
361 /* If we need randomisation in the solve, this is our random state. */
363 /* Number of solutions so far found, and maximum number we care about. */
368 * The real recursive step in the solving function.
370 static void rsolve_real(struct rsolve_usage *usage, digit *grid)
372 int c = usage->c, r = usage->r, cr = usage->cr;
373 int i, j, n, sx, sy, bestm, bestr;
377 * Firstly, check for completion! If there are no spaces left
378 * in the grid, we have a solution.
380 if (usage->nspaces == 0) {
383 * This is our first solution, so fill in the output grid.
385 memcpy(grid, usage->grid, cr * cr);
392 * Otherwise, there must be at least one space. Find the most
393 * constrained space, using the `r' field as a tie-breaker.
395 bestm = cr+1; /* so that any space will beat it */
398 for (j = 0; j < usage->nspaces; j++) {
399 int x = usage->spaces[j].x, y = usage->spaces[j].y;
403 * Find the number of digits that could go in this space.
406 for (n = 0; n < cr; n++)
407 if (!usage->row[y*cr+n] && !usage->col[x*cr+n] &&
408 !usage->blk[((y/c)*c+(x/r))*cr+n])
411 if (m < bestm || (m == bestm && usage->spaces[j].r < bestr)) {
413 bestr = usage->spaces[j].r;
421 * Swap that square into the final place in the spaces array,
422 * so that decrementing nspaces will remove it from the list.
424 if (i != usage->nspaces-1) {
425 struct rsolve_coord t;
426 t = usage->spaces[usage->nspaces-1];
427 usage->spaces[usage->nspaces-1] = usage->spaces[i];
428 usage->spaces[i] = t;
432 * Now we've decided which square to start our recursion at,
433 * simply go through all possible values, shuffling them
434 * randomly first if necessary.
436 digits = snewn(bestm, int);
438 for (n = 0; n < cr; n++)
439 if (!usage->row[sy*cr+n] && !usage->col[sx*cr+n] &&
440 !usage->blk[((sy/c)*c+(sx/r))*cr+n]) {
446 for (i = j; i > 1; i--) {
447 int p = random_upto(usage->rs, i);
450 digits[p] = digits[i-1];
456 /* And finally, go through the digit list and actually recurse. */
457 for (i = 0; i < j; i++) {
460 /* Update the usage structure to reflect the placing of this digit. */
461 usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] =
462 usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = TRUE;
463 usage->grid[sy*cr+sx] = n;
466 /* Call the solver recursively. */
467 rsolve_real(usage, grid);
470 * If we have seen as many solutions as we need, terminate
471 * all processing immediately.
473 if (usage->solns >= usage->maxsolns)
476 /* Revert the usage structure. */
477 usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] =
478 usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = FALSE;
479 usage->grid[sy*cr+sx] = 0;
487 * Entry point to solver. You give it dimensions and a starting
488 * grid, which is simply an array of N^4 digits. In that array, 0
489 * means an empty square, and 1..N mean a clue square.
491 * Return value is the number of solutions found; searching will
492 * stop after the provided `max'. (Thus, you can pass max==1 to
493 * indicate that you only care about finding _one_ solution, or
494 * max==2 to indicate that you want to know the difference between
495 * a unique and non-unique solution.) The input parameter `grid' is
496 * also filled in with the _first_ (or only) solution found by the
499 static int rsolve(int c, int r, digit *grid, random_state *rs, int max)
501 struct rsolve_usage *usage;
506 * Create an rsolve_usage structure.
508 usage = snew(struct rsolve_usage);
514 usage->grid = snewn(cr * cr, digit);
515 memcpy(usage->grid, grid, cr * cr);
517 usage->row = snewn(cr * cr, unsigned char);
518 usage->col = snewn(cr * cr, unsigned char);
519 usage->blk = snewn(cr * cr, unsigned char);
520 memset(usage->row, FALSE, cr * cr);
521 memset(usage->col, FALSE, cr * cr);
522 memset(usage->blk, FALSE, cr * cr);
524 usage->spaces = snewn(cr * cr, struct rsolve_coord);
528 usage->maxsolns = max;
533 * Now fill it in with data from the input grid.
535 for (y = 0; y < cr; y++) {
536 for (x = 0; x < cr; x++) {
537 int v = grid[y*cr+x];
539 usage->spaces[usage->nspaces].x = x;
540 usage->spaces[usage->nspaces].y = y;
542 usage->spaces[usage->nspaces].r = random_bits(rs, 31);
544 usage->spaces[usage->nspaces].r = usage->nspaces;
547 usage->row[y*cr+v-1] = TRUE;
548 usage->col[x*cr+v-1] = TRUE;
549 usage->blk[((y/c)*c+(x/r))*cr+v-1] = TRUE;
555 * Run the real recursive solving function.
557 rsolve_real(usage, grid);
561 * Clean up the usage structure now we have our answer.
563 sfree(usage->spaces);
576 /* ----------------------------------------------------------------------
577 * End of recursive solver code.
580 /* ----------------------------------------------------------------------
581 * Less capable non-recursive solver. This one is used to check
582 * solubility of a grid as we gradually remove numbers from it: by
583 * verifying a grid using this solver we can ensure it isn't _too_
584 * hard (e.g. does not actually require guessing and backtracking).
586 * It supports a variety of specific modes of reasoning. By
587 * enabling or disabling subsets of these modes we can arrange a
588 * range of difficulty levels.
592 * Modes of reasoning currently supported:
594 * - Positional elimination: a number must go in a particular
595 * square because all the other empty squares in a given
596 * row/col/blk are ruled out.
598 * - Numeric elimination: a square must have a particular number
599 * in because all the other numbers that could go in it are
602 * - Intersectional analysis: given two domains which overlap
603 * (hence one must be a block, and the other can be a row or
604 * col), if the possible locations for a particular number in
605 * one of the domains can be narrowed down to the overlap, then
606 * that number can be ruled out everywhere but the overlap in
607 * the other domain too.
609 * - Set elimination: if there is a subset of the empty squares
610 * within a domain such that the union of the possible numbers
611 * in that subset has the same size as the subset itself, then
612 * those numbers can be ruled out everywhere else in the domain.
613 * (For example, if there are five empty squares and the
614 * possible numbers in each are 12, 23, 13, 134 and 1345, then
615 * the first three empty squares form such a subset: the numbers
616 * 1, 2 and 3 _must_ be in those three squares in some
617 * permutation, and hence we can deduce none of them can be in
618 * the fourth or fifth squares.)
619 * + You can also see this the other way round, concentrating
620 * on numbers rather than squares: if there is a subset of
621 * the unplaced numbers within a domain such that the union
622 * of all their possible positions has the same size as the
623 * subset itself, then all other numbers can be ruled out for
624 * those positions. However, it turns out that this is
625 * exactly equivalent to the first formulation at all times:
626 * there is a 1-1 correspondence between suitable subsets of
627 * the unplaced numbers and suitable subsets of the unfilled
628 * places, found by taking the _complement_ of the union of
629 * the numbers' possible positions (or the spaces' possible
634 * Within this solver, I'm going to transform all y-coordinates by
635 * inverting the significance of the block number and the position
636 * within the block. That is, we will start with the top row of
637 * each block in order, then the second row of each block in order,
640 * This transformation has the enormous advantage that it means
641 * every row, column _and_ block is described by an arithmetic
642 * progression of coordinates within the cubic array, so that I can
643 * use the same very simple function to do blockwise, row-wise and
644 * column-wise elimination.
646 #define YTRANS(y) (((y)%c)*r+(y)/c)
647 #define YUNTRANS(y) (((y)%r)*c+(y)/r)
649 struct nsolve_usage {
652 * We set up a cubic array, indexed by x, y and digit; each
653 * element of this array is TRUE or FALSE according to whether
654 * or not that digit _could_ in principle go in that position.
656 * The way to index this array is cube[(x*cr+y)*cr+n-1].
657 * y-coordinates in here are transformed.
661 * This is the grid in which we write down our final
662 * deductions. y-coordinates in here are _not_ transformed.
666 * Now we keep track, at a slightly higher level, of what we
667 * have yet to work out, to prevent doing the same deduction
670 /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
672 /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
674 /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
677 #define cubepos(x,y,n) (((x)*usage->cr+(y))*usage->cr+(n)-1)
678 #define cube(x,y,n) (usage->cube[cubepos(x,y,n)])
681 * Function called when we are certain that a particular square has
682 * a particular number in it. The y-coordinate passed in here is
685 static void nsolve_place(struct nsolve_usage *usage, int x, int y, int n)
687 int c = usage->c, r = usage->r, cr = usage->cr;
693 * Rule out all other numbers in this square.
695 for (i = 1; i <= cr; i++)
700 * Rule out this number in all other positions in the row.
702 for (i = 0; i < cr; i++)
707 * Rule out this number in all other positions in the column.
709 for (i = 0; i < cr; i++)
714 * Rule out this number in all other positions in the block.
718 for (i = 0; i < r; i++)
719 for (j = 0; j < c; j++)
720 if (bx+i != x || by+j*r != y)
721 cube(bx+i,by+j*r,n) = FALSE;
724 * Enter the number in the result grid.
726 usage->grid[YUNTRANS(y)*cr+x] = n;
729 * Cross out this number from the list of numbers left to place
730 * in its row, its column and its block.
732 usage->row[y*cr+n-1] = usage->col[x*cr+n-1] =
733 usage->blk[((y%r)*c+(x/r))*cr+n-1] = TRUE;
736 static int nsolve_elim(struct nsolve_usage *usage, int start, int step
737 #ifdef STANDALONE_SOLVER
742 int c = usage->c, r = usage->r, cr = c*r;
746 * Count the number of set bits within this section of the
751 for (i = 0; i < cr; i++)
752 if (usage->cube[start+i*step]) {
766 if (!usage->grid[YUNTRANS(y)*cr+x]) {
767 #ifdef STANDALONE_SOLVER
768 if (solver_show_working) {
773 printf(":\n placing %d at (%d,%d)\n",
774 n, 1+x, 1+YUNTRANS(y));
777 nsolve_place(usage, x, y, n);
785 static int nsolve_intersect(struct nsolve_usage *usage,
786 int start1, int step1, int start2, int step2
787 #ifdef STANDALONE_SOLVER
792 int c = usage->c, r = usage->r, cr = c*r;
796 * Loop over the first domain and see if there's any set bit
797 * not also in the second.
799 for (i = 0; i < cr; i++) {
800 int p = start1+i*step1;
801 if (usage->cube[p] &&
802 !(p >= start2 && p < start2+cr*step2 &&
803 (p - start2) % step2 == 0))
804 return FALSE; /* there is, so we can't deduce */
808 * We have determined that all set bits in the first domain are
809 * within its overlap with the second. So loop over the second
810 * domain and remove all set bits that aren't also in that
811 * overlap; return TRUE iff we actually _did_ anything.
814 for (i = 0; i < cr; i++) {
815 int p = start2+i*step2;
816 if (usage->cube[p] &&
817 !(p >= start1 && p < start1+cr*step1 && (p - start1) % step1 == 0))
819 #ifdef STANDALONE_SOLVER
820 if (solver_show_working) {
836 printf(" ruling out %d at (%d,%d)\n",
837 pn, 1+px, 1+YUNTRANS(py));
840 ret = TRUE; /* we did something */
848 struct nsolve_scratch {
849 unsigned char *grid, *rowidx, *colidx, *set;
852 static int nsolve_set(struct nsolve_usage *usage,
853 struct nsolve_scratch *scratch,
854 int start, int step1, int step2
855 #ifdef STANDALONE_SOLVER
860 int c = usage->c, r = usage->r, cr = c*r;
862 unsigned char *grid = scratch->grid;
863 unsigned char *rowidx = scratch->rowidx;
864 unsigned char *colidx = scratch->colidx;
865 unsigned char *set = scratch->set;
868 * We are passed a cr-by-cr matrix of booleans. Our first job
869 * is to winnow it by finding any definite placements - i.e.
870 * any row with a solitary 1 - and discarding that row and the
871 * column containing the 1.
873 memset(rowidx, TRUE, cr);
874 memset(colidx, TRUE, cr);
875 for (i = 0; i < cr; i++) {
876 int count = 0, first = -1;
877 for (j = 0; j < cr; j++)
878 if (usage->cube[start+i*step1+j*step2])
882 * This condition actually marks a completely insoluble
883 * (i.e. internally inconsistent) puzzle. We return and
884 * report no progress made.
889 rowidx[i] = colidx[first] = FALSE;
893 * Convert each of rowidx/colidx from a list of 0s and 1s to a
894 * list of the indices of the 1s.
896 for (i = j = 0; i < cr; i++)
900 for (i = j = 0; i < cr; i++)
906 * And create the smaller matrix.
908 for (i = 0; i < n; i++)
909 for (j = 0; j < n; j++)
910 grid[i*cr+j] = usage->cube[start+rowidx[i]*step1+colidx[j]*step2];
913 * Having done that, we now have a matrix in which every row
914 * has at least two 1s in. Now we search to see if we can find
915 * a rectangle of zeroes (in the set-theoretic sense of
916 * `rectangle', i.e. a subset of rows crossed with a subset of
917 * columns) whose width and height add up to n.
924 * We have a candidate set. If its size is <=1 or >=n-1
925 * then we move on immediately.
927 if (count > 1 && count < n-1) {
929 * The number of rows we need is n-count. See if we can
930 * find that many rows which each have a zero in all
931 * the positions listed in `set'.
934 for (i = 0; i < n; i++) {
936 for (j = 0; j < n; j++)
937 if (set[j] && grid[i*cr+j]) {
946 * We expect never to be able to get _more_ than
947 * n-count suitable rows: this would imply that (for
948 * example) there are four numbers which between them
949 * have at most three possible positions, and hence it
950 * indicates a faulty deduction before this point or
953 assert(rows <= n - count);
954 if (rows >= n - count) {
955 int progress = FALSE;
958 * We've got one! Now, for each row which _doesn't_
959 * satisfy the criterion, eliminate all its set
960 * bits in the positions _not_ listed in `set'.
961 * Return TRUE (meaning progress has been made) if
962 * we successfully eliminated anything at all.
964 * This involves referring back through
965 * rowidx/colidx in order to work out which actual
966 * positions in the cube to meddle with.
968 for (i = 0; i < n; i++) {
970 for (j = 0; j < n; j++)
971 if (set[j] && grid[i*cr+j]) {
976 for (j = 0; j < n; j++)
977 if (!set[j] && grid[i*cr+j]) {
978 int fpos = (start+rowidx[i]*step1+
980 #ifdef STANDALONE_SOLVER
981 if (solver_show_working) {
997 printf(" ruling out %d at (%d,%d)\n",
998 pn, 1+px, 1+YUNTRANS(py));
1002 usage->cube[fpos] = FALSE;
1014 * Binary increment: change the rightmost 0 to a 1, and
1015 * change all 1s to the right of it to 0s.
1018 while (i > 0 && set[i-1])
1019 set[--i] = 0, count--;
1021 set[--i] = 1, count++;
1029 static struct nsolve_scratch *nsolve_new_scratch(struct nsolve_usage *usage)
1031 struct nsolve_scratch *scratch = snew(struct nsolve_scratch);
1033 scratch->grid = snewn(cr*cr, unsigned char);
1034 scratch->rowidx = snewn(cr, unsigned char);
1035 scratch->colidx = snewn(cr, unsigned char);
1036 scratch->set = snewn(cr, unsigned char);
1040 static void nsolve_free_scratch(struct nsolve_scratch *scratch)
1042 sfree(scratch->set);
1043 sfree(scratch->colidx);
1044 sfree(scratch->rowidx);
1045 sfree(scratch->grid);
1049 static int nsolve(int c, int r, digit *grid)
1051 struct nsolve_usage *usage;
1052 struct nsolve_scratch *scratch;
1055 int diff = DIFF_BLOCK;
1058 * Set up a usage structure as a clean slate (everything
1061 usage = snew(struct nsolve_usage);
1065 usage->cube = snewn(cr*cr*cr, unsigned char);
1066 usage->grid = grid; /* write straight back to the input */
1067 memset(usage->cube, TRUE, cr*cr*cr);
1069 usage->row = snewn(cr * cr, unsigned char);
1070 usage->col = snewn(cr * cr, unsigned char);
1071 usage->blk = snewn(cr * cr, unsigned char);
1072 memset(usage->row, FALSE, cr * cr);
1073 memset(usage->col, FALSE, cr * cr);
1074 memset(usage->blk, FALSE, cr * cr);
1076 scratch = nsolve_new_scratch(usage);
1079 * Place all the clue numbers we are given.
1081 for (x = 0; x < cr; x++)
1082 for (y = 0; y < cr; y++)
1084 nsolve_place(usage, x, YTRANS(y), grid[y*cr+x]);
1087 * Now loop over the grid repeatedly trying all permitted modes
1088 * of reasoning. The loop terminates if we complete an
1089 * iteration without making any progress; we then return
1090 * failure or success depending on whether the grid is full or
1095 * I'd like to write `continue;' inside each of the
1096 * following loops, so that the solver returns here after
1097 * making some progress. However, I can't specify that I
1098 * want to continue an outer loop rather than the innermost
1099 * one, so I'm apologetically resorting to a goto.
1104 * Blockwise positional elimination.
1106 for (x = 0; x < cr; x += r)
1107 for (y = 0; y < r; y++)
1108 for (n = 1; n <= cr; n++)
1109 if (!usage->blk[(y*c+(x/r))*cr+n-1] &&
1110 nsolve_elim(usage, cubepos(x,y,n), r*cr
1111 #ifdef STANDALONE_SOLVER
1112 , "positional elimination,"
1113 " block (%d,%d)", 1+x/r, 1+y
1116 diff = max(diff, DIFF_BLOCK);
1121 * Row-wise positional elimination.
1123 for (y = 0; y < cr; y++)
1124 for (n = 1; n <= cr; n++)
1125 if (!usage->row[y*cr+n-1] &&
1126 nsolve_elim(usage, cubepos(0,y,n), cr*cr
1127 #ifdef STANDALONE_SOLVER
1128 , "positional elimination,"
1129 " row %d", 1+YUNTRANS(y)
1132 diff = max(diff, DIFF_SIMPLE);
1136 * Column-wise positional elimination.
1138 for (x = 0; x < cr; x++)
1139 for (n = 1; n <= cr; n++)
1140 if (!usage->col[x*cr+n-1] &&
1141 nsolve_elim(usage, cubepos(x,0,n), cr
1142 #ifdef STANDALONE_SOLVER
1143 , "positional elimination," " column %d", 1+x
1146 diff = max(diff, DIFF_SIMPLE);
1151 * Numeric elimination.
1153 for (x = 0; x < cr; x++)
1154 for (y = 0; y < cr; y++)
1155 if (!usage->grid[YUNTRANS(y)*cr+x] &&
1156 nsolve_elim(usage, cubepos(x,y,1), 1
1157 #ifdef STANDALONE_SOLVER
1158 , "numeric elimination at (%d,%d)", 1+x,
1162 diff = max(diff, DIFF_SIMPLE);
1167 * Intersectional analysis, rows vs blocks.
1169 for (y = 0; y < cr; y++)
1170 for (x = 0; x < cr; x += r)
1171 for (n = 1; n <= cr; n++)
1172 if (!usage->row[y*cr+n-1] &&
1173 !usage->blk[((y%r)*c+(x/r))*cr+n-1] &&
1174 (nsolve_intersect(usage, cubepos(0,y,n), cr*cr,
1175 cubepos(x,y%r,n), r*cr
1176 #ifdef STANDALONE_SOLVER
1177 , "intersectional analysis,"
1178 " row %d vs block (%d,%d)",
1179 1+YUNTRANS(y), 1+x/r, 1+y%r
1182 nsolve_intersect(usage, cubepos(x,y%r,n), r*cr,
1183 cubepos(0,y,n), cr*cr
1184 #ifdef STANDALONE_SOLVER
1185 , "intersectional analysis,"
1186 " block (%d,%d) vs row %d",
1187 1+x/r, 1+y%r, 1+YUNTRANS(y)
1190 diff = max(diff, DIFF_INTERSECT);
1195 * Intersectional analysis, columns vs blocks.
1197 for (x = 0; x < cr; x++)
1198 for (y = 0; y < r; y++)
1199 for (n = 1; n <= cr; n++)
1200 if (!usage->col[x*cr+n-1] &&
1201 !usage->blk[(y*c+(x/r))*cr+n-1] &&
1202 (nsolve_intersect(usage, cubepos(x,0,n), cr,
1203 cubepos((x/r)*r,y,n), r*cr
1204 #ifdef STANDALONE_SOLVER
1205 , "intersectional analysis,"
1206 " column %d vs block (%d,%d)",
1210 nsolve_intersect(usage, cubepos((x/r)*r,y,n), r*cr,
1212 #ifdef STANDALONE_SOLVER
1213 , "intersectional analysis,"
1214 " block (%d,%d) vs column %d",
1218 diff = max(diff, DIFF_INTERSECT);
1223 * Blockwise set elimination.
1225 for (x = 0; x < cr; x += r)
1226 for (y = 0; y < r; y++)
1227 if (nsolve_set(usage, scratch, cubepos(x,y,1), r*cr, 1
1228 #ifdef STANDALONE_SOLVER
1229 , "set elimination, block (%d,%d)", 1+x/r, 1+y
1232 diff = max(diff, DIFF_SET);
1237 * Row-wise set elimination.
1239 for (y = 0; y < cr; y++)
1240 if (nsolve_set(usage, scratch, cubepos(0,y,1), cr*cr, 1
1241 #ifdef STANDALONE_SOLVER
1242 , "set elimination, row %d", 1+YUNTRANS(y)
1245 diff = max(diff, DIFF_SET);
1250 * Column-wise set elimination.
1252 for (x = 0; x < cr; x++)
1253 if (nsolve_set(usage, scratch, cubepos(x,0,1), cr, 1
1254 #ifdef STANDALONE_SOLVER
1255 , "set elimination, column %d", 1+x
1258 diff = max(diff, DIFF_SET);
1263 * If we reach here, we have made no deductions in this
1264 * iteration, so the algorithm terminates.
1269 nsolve_free_scratch(scratch);
1277 for (x = 0; x < cr; x++)
1278 for (y = 0; y < cr; y++)
1280 return DIFF_IMPOSSIBLE;
1284 /* ----------------------------------------------------------------------
1285 * End of non-recursive solver code.
1289 * Check whether a grid contains a valid complete puzzle.
1291 static int check_valid(int c, int r, digit *grid)
1294 unsigned char *used;
1297 used = snewn(cr, unsigned char);
1300 * Check that each row contains precisely one of everything.
1302 for (y = 0; y < cr; y++) {
1303 memset(used, FALSE, cr);
1304 for (x = 0; x < cr; x++)
1305 if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr)
1306 used[grid[y*cr+x]-1] = TRUE;
1307 for (n = 0; n < cr; n++)
1315 * Check that each column contains precisely one of everything.
1317 for (x = 0; x < cr; x++) {
1318 memset(used, FALSE, cr);
1319 for (y = 0; y < cr; y++)
1320 if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr)
1321 used[grid[y*cr+x]-1] = TRUE;
1322 for (n = 0; n < cr; n++)
1330 * Check that each block contains precisely one of everything.
1332 for (x = 0; x < cr; x += r) {
1333 for (y = 0; y < cr; y += c) {
1335 memset(used, FALSE, cr);
1336 for (xx = x; xx < x+r; xx++)
1337 for (yy = 0; yy < y+c; yy++)
1338 if (grid[yy*cr+xx] > 0 && grid[yy*cr+xx] <= cr)
1339 used[grid[yy*cr+xx]-1] = TRUE;
1340 for (n = 0; n < cr; n++)
1352 static void symmetry_limit(game_params *params, int *xlim, int *ylim, int s)
1354 int c = params->c, r = params->r, cr = c*r;
1366 *xlim = *ylim = (cr+1) / 2;
1371 static int symmetries(game_params *params, int x, int y, int *output, int s)
1373 int c = params->c, r = params->r, cr = c*r;
1382 break; /* just x,y is all we need */
1387 *output++ = cr - 1 - x;
1392 *output++ = cr - 1 - y;
1396 *output++ = cr - 1 - y;
1401 *output++ = cr - 1 - x;
1407 *output++ = cr - 1 - x;
1408 *output++ = cr - 1 - y;
1416 struct game_aux_info {
1421 static char *new_game_desc(game_params *params, random_state *rs,
1422 game_aux_info **aux, int interactive)
1424 int c = params->c, r = params->r, cr = c*r;
1426 digit *grid, *grid2;
1427 struct xy { int x, y; } *locs;
1431 int coords[16], ncoords;
1433 int maxdiff, recursing;
1436 * Adjust the maximum difficulty level to be consistent with
1437 * the puzzle size: all 2x2 puzzles appear to be Trivial
1438 * (DIFF_BLOCK) so we cannot hold out for even a Basic
1439 * (DIFF_SIMPLE) one.
1441 maxdiff = params->diff;
1442 if (c == 2 && r == 2)
1443 maxdiff = DIFF_BLOCK;
1445 grid = snewn(area, digit);
1446 locs = snewn(area, struct xy);
1447 grid2 = snewn(area, digit);
1450 * Loop until we get a grid of the required difficulty. This is
1451 * nasty, but it seems to be unpleasantly hard to generate
1452 * difficult grids otherwise.
1456 * Start the recursive solver with an empty grid to generate a
1457 * random solved state.
1459 memset(grid, 0, area);
1460 ret = rsolve(c, r, grid, rs, 1);
1462 assert(check_valid(c, r, grid));
1465 * Save the solved grid in the aux_info.
1468 game_aux_info *ai = snew(game_aux_info);
1471 ai->grid = snewn(cr * cr, digit);
1472 memcpy(ai->grid, grid, cr * cr * sizeof(digit));
1474 * We might already have written *aux the last time we
1475 * went round this loop, in which case we should free
1476 * the old aux_info before overwriting it with the new
1480 sfree((*aux)->grid);
1487 * Now we have a solved grid, start removing things from it
1488 * while preserving solubility.
1490 symmetry_limit(params, &xlim, &ylim, params->symm);
1496 * Iterate over the grid and enumerate all the filled
1497 * squares we could empty.
1501 for (x = 0; x < xlim; x++)
1502 for (y = 0; y < ylim; y++)
1510 * Now shuffle that list.
1512 for (i = nlocs; i > 1; i--) {
1513 int p = random_upto(rs, i);
1515 struct xy t = locs[p];
1516 locs[p] = locs[i-1];
1522 * Now loop over the shuffled list and, for each element,
1523 * see whether removing that element (and its reflections)
1524 * from the grid will still leave the grid soluble by
1527 for (i = 0; i < nlocs; i++) {
1533 memcpy(grid2, grid, area);
1534 ncoords = symmetries(params, x, y, coords, params->symm);
1535 for (j = 0; j < ncoords; j++)
1536 grid2[coords[2*j+1]*cr+coords[2*j]] = 0;
1539 ret = (rsolve(c, r, grid2, NULL, 2) == 1);
1541 ret = (nsolve(c, r, grid2) <= maxdiff);
1544 for (j = 0; j < ncoords; j++)
1545 grid[coords[2*j+1]*cr+coords[2*j]] = 0;
1552 * There was nothing we could remove without
1553 * destroying solvability. If we're trying to
1554 * generate a recursion-only grid and haven't
1555 * switched over to rsolve yet, we now do;
1556 * otherwise we give up.
1558 if (maxdiff == DIFF_RECURSIVE && !recursing) {
1566 memcpy(grid2, grid, area);
1567 } while (nsolve(c, r, grid2) < maxdiff);
1573 * Now we have the grid as it will be presented to the user.
1574 * Encode it in a game desc.
1580 desc = snewn(5 * area, char);
1583 for (i = 0; i <= area; i++) {
1584 int n = (i < area ? grid[i] : -1);
1591 int c = 'a' - 1 + run;
1595 run -= c - ('a' - 1);
1599 * If there's a number in the very top left or
1600 * bottom right, there's no point putting an
1601 * unnecessary _ before or after it.
1603 if (p > desc && n > 0)
1607 p += sprintf(p, "%d", n);
1611 assert(p - desc < 5 * area);
1613 desc = sresize(desc, p - desc, char);
1621 static void game_free_aux_info(game_aux_info *aux)
1627 static char *validate_desc(game_params *params, char *desc)
1629 int area = params->r * params->r * params->c * params->c;
1634 if (n >= 'a' && n <= 'z') {
1635 squares += n - 'a' + 1;
1636 } else if (n == '_') {
1638 } else if (n > '0' && n <= '9') {
1640 while (*desc >= '0' && *desc <= '9')
1643 return "Invalid character in game description";
1647 return "Not enough data to fill grid";
1650 return "Too much data to fit in grid";
1655 static game_state *new_game(midend_data *me, game_params *params, char *desc)
1657 game_state *state = snew(game_state);
1658 int c = params->c, r = params->r, cr = c*r, area = cr * cr;
1661 state->c = params->c;
1662 state->r = params->r;
1664 state->grid = snewn(area, digit);
1665 state->pencil = snewn(area * cr, unsigned char);
1666 memset(state->pencil, 0, area * cr);
1667 state->immutable = snewn(area, unsigned char);
1668 memset(state->immutable, FALSE, area);
1670 state->completed = state->cheated = FALSE;
1675 if (n >= 'a' && n <= 'z') {
1676 int run = n - 'a' + 1;
1677 assert(i + run <= area);
1679 state->grid[i++] = 0;
1680 } else if (n == '_') {
1682 } else if (n > '0' && n <= '9') {
1684 state->immutable[i] = TRUE;
1685 state->grid[i++] = atoi(desc-1);
1686 while (*desc >= '0' && *desc <= '9')
1689 assert(!"We can't get here");
1697 static game_state *dup_game(game_state *state)
1699 game_state *ret = snew(game_state);
1700 int c = state->c, r = state->r, cr = c*r, area = cr * cr;
1705 ret->grid = snewn(area, digit);
1706 memcpy(ret->grid, state->grid, area);
1708 ret->pencil = snewn(area * cr, unsigned char);
1709 memcpy(ret->pencil, state->pencil, area * cr);
1711 ret->immutable = snewn(area, unsigned char);
1712 memcpy(ret->immutable, state->immutable, area);
1714 ret->completed = state->completed;
1715 ret->cheated = state->cheated;
1720 static void free_game(game_state *state)
1722 sfree(state->immutable);
1723 sfree(state->pencil);
1728 static game_state *solve_game(game_state *state, game_aux_info *ai,
1732 int c = state->c, r = state->r, cr = c*r;
1735 ret = dup_game(state);
1736 ret->completed = ret->cheated = TRUE;
1739 * If we already have the solution in the aux_info, save
1740 * ourselves some time.
1746 memcpy(ret->grid, ai->grid, cr * cr * sizeof(digit));
1749 rsolve_ret = rsolve(c, r, ret->grid, NULL, 2);
1751 if (rsolve_ret != 1) {
1753 if (rsolve_ret == 0)
1754 *error = "No solution exists for this puzzle";
1756 *error = "Multiple solutions exist for this puzzle";
1764 static char *grid_text_format(int c, int r, digit *grid)
1772 * There are cr lines of digits, plus r-1 lines of block
1773 * separators. Each line contains cr digits, cr-1 separating
1774 * spaces, and c-1 two-character block separators. Thus, the
1775 * total length of a line is 2*cr+2*c-3 (not counting the
1776 * newline), and there are cr+r-1 of them.
1778 maxlen = (cr+r-1) * (2*cr+2*c-2);
1779 ret = snewn(maxlen+1, char);
1782 for (y = 0; y < cr; y++) {
1783 for (x = 0; x < cr; x++) {
1784 int ch = grid[y * cr + x];
1794 if ((x+1) % r == 0) {
1801 if (y+1 < cr && (y+1) % c == 0) {
1802 for (x = 0; x < cr; x++) {
1806 if ((x+1) % r == 0) {
1816 assert(p - ret == maxlen);
1821 static char *game_text_format(game_state *state)
1823 return grid_text_format(state->c, state->r, state->grid);
1828 * These are the coordinates of the currently highlighted
1829 * square on the grid, or -1,-1 if there isn't one. When there
1830 * is, pressing a valid number or letter key or Space will
1831 * enter that number or letter in the grid.
1835 * This indicates whether the current highlight is a
1836 * pencil-mark one or a real one.
1841 static game_ui *new_ui(game_state *state)
1843 game_ui *ui = snew(game_ui);
1845 ui->hx = ui->hy = -1;
1851 static void free_ui(game_ui *ui)
1856 static game_state *make_move(game_state *from, game_ui *ui, game_drawstate *ds,
1857 int x, int y, int button)
1859 int c = from->c, r = from->r, cr = c*r;
1863 button &= ~MOD_MASK;
1865 tx = (x + TILE_SIZE - BORDER) / TILE_SIZE - 1;
1866 ty = (y + TILE_SIZE - BORDER) / TILE_SIZE - 1;
1868 if (tx >= 0 && tx < cr && ty >= 0 && ty < cr) {
1869 if (button == LEFT_BUTTON) {
1870 if (from->immutable[ty*cr+tx]) {
1871 ui->hx = ui->hy = -1;
1872 } else if (tx == ui->hx && ty == ui->hy && ui->hpencil == 0) {
1873 ui->hx = ui->hy = -1;
1879 return from; /* UI activity occurred */
1881 if (button == RIGHT_BUTTON) {
1883 * Pencil-mode highlighting for non filled squares.
1885 if (from->grid[ty*cr+tx] == 0) {
1886 if (tx == ui->hx && ty == ui->hy && ui->hpencil) {
1887 ui->hx = ui->hy = -1;
1894 ui->hx = ui->hy = -1;
1896 return from; /* UI activity occurred */
1900 if (ui->hx != -1 && ui->hy != -1 &&
1901 ((button >= '1' && button <= '9' && button - '0' <= cr) ||
1902 (button >= 'a' && button <= 'z' && button - 'a' + 10 <= cr) ||
1903 (button >= 'A' && button <= 'Z' && button - 'A' + 10 <= cr) ||
1905 int n = button - '0';
1906 if (button >= 'A' && button <= 'Z')
1907 n = button - 'A' + 10;
1908 if (button >= 'a' && button <= 'z')
1909 n = button - 'a' + 10;
1914 * Can't overwrite this square. In principle this shouldn't
1915 * happen anyway because we should never have even been
1916 * able to highlight the square, but it never hurts to be
1919 if (from->immutable[ui->hy*cr+ui->hx])
1923 * Can't make pencil marks in a filled square. In principle
1924 * this shouldn't happen anyway because we should never
1925 * have even been able to pencil-highlight the square, but
1926 * it never hurts to be careful.
1928 if (ui->hpencil && from->grid[ui->hy*cr+ui->hx])
1931 ret = dup_game(from);
1932 if (ui->hpencil && n > 0) {
1933 int index = (ui->hy*cr+ui->hx) * cr + (n-1);
1934 ret->pencil[index] = !ret->pencil[index];
1936 ret->grid[ui->hy*cr+ui->hx] = n;
1937 memset(ret->pencil + (ui->hy*cr+ui->hx)*cr, 0, cr);
1940 * We've made a real change to the grid. Check to see
1941 * if the game has been completed.
1943 if (!ret->completed && check_valid(c, r, ret->grid)) {
1944 ret->completed = TRUE;
1947 ui->hx = ui->hy = -1;
1949 return ret; /* made a valid move */
1955 /* ----------------------------------------------------------------------
1959 struct game_drawstate {
1963 unsigned char *pencil;
1967 #define XSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
1968 #define YSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
1970 static void game_size(game_params *params, int *x, int *y)
1972 int c = params->c, r = params->r, cr = c*r;
1978 static float *game_colours(frontend *fe, game_state *state, int *ncolours)
1980 float *ret = snewn(3 * NCOLOURS, float);
1982 frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
1984 ret[COL_GRID * 3 + 0] = 0.0F;
1985 ret[COL_GRID * 3 + 1] = 0.0F;
1986 ret[COL_GRID * 3 + 2] = 0.0F;
1988 ret[COL_CLUE * 3 + 0] = 0.0F;
1989 ret[COL_CLUE * 3 + 1] = 0.0F;
1990 ret[COL_CLUE * 3 + 2] = 0.0F;
1992 ret[COL_USER * 3 + 0] = 0.0F;
1993 ret[COL_USER * 3 + 1] = 0.6F * ret[COL_BACKGROUND * 3 + 1];
1994 ret[COL_USER * 3 + 2] = 0.0F;
1996 ret[COL_HIGHLIGHT * 3 + 0] = 0.85F * ret[COL_BACKGROUND * 3 + 0];
1997 ret[COL_HIGHLIGHT * 3 + 1] = 0.85F * ret[COL_BACKGROUND * 3 + 1];
1998 ret[COL_HIGHLIGHT * 3 + 2] = 0.85F * ret[COL_BACKGROUND * 3 + 2];
2000 ret[COL_ERROR * 3 + 0] = 1.0F;
2001 ret[COL_ERROR * 3 + 1] = 0.0F;
2002 ret[COL_ERROR * 3 + 2] = 0.0F;
2004 ret[COL_PENCIL * 3 + 0] = 0.5F * ret[COL_BACKGROUND * 3 + 0];
2005 ret[COL_PENCIL * 3 + 1] = 0.5F * ret[COL_BACKGROUND * 3 + 1];
2006 ret[COL_PENCIL * 3 + 2] = ret[COL_BACKGROUND * 3 + 2];
2008 *ncolours = NCOLOURS;
2012 static game_drawstate *game_new_drawstate(game_state *state)
2014 struct game_drawstate *ds = snew(struct game_drawstate);
2015 int c = state->c, r = state->r, cr = c*r;
2017 ds->started = FALSE;
2021 ds->grid = snewn(cr*cr, digit);
2022 memset(ds->grid, 0, cr*cr);
2023 ds->pencil = snewn(cr*cr*cr, digit);
2024 memset(ds->pencil, 0, cr*cr*cr);
2025 ds->hl = snewn(cr*cr, unsigned char);
2026 memset(ds->hl, 0, cr*cr);
2031 static void game_free_drawstate(game_drawstate *ds)
2039 static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
2040 int x, int y, int hl)
2042 int c = state->c, r = state->r, cr = c*r;
2047 if (ds->grid[y*cr+x] == state->grid[y*cr+x] &&
2048 ds->hl[y*cr+x] == hl &&
2049 !memcmp(ds->pencil+(y*cr+x)*cr, state->pencil+(y*cr+x)*cr, cr))
2050 return; /* no change required */
2052 tx = BORDER + x * TILE_SIZE + 2;
2053 ty = BORDER + y * TILE_SIZE + 2;
2069 clip(fe, cx, cy, cw, ch);
2071 /* background needs erasing */
2072 draw_rect(fe, cx, cy, cw, ch, (hl & 15) == 1 ? COL_HIGHLIGHT : COL_BACKGROUND);
2074 /* pencil-mode highlight */
2075 if ((hl & 15) == 2) {
2079 coords[2] = cx+cw/2;
2082 coords[5] = cy+ch/2;
2083 draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
2086 /* new number needs drawing? */
2087 if (state->grid[y*cr+x]) {
2089 str[0] = state->grid[y*cr+x] + '0';
2091 str[0] += 'a' - ('9'+1);
2092 draw_text(fe, tx + TILE_SIZE/2, ty + TILE_SIZE/2,
2093 FONT_VARIABLE, TILE_SIZE/2, ALIGN_VCENTRE | ALIGN_HCENTRE,
2094 state->immutable[y*cr+x] ? COL_CLUE : (hl & 16) ? COL_ERROR : COL_USER, str);
2096 /* pencil marks required? */
2099 for (i = j = 0; i < cr; i++)
2100 if (state->pencil[(y*cr+x)*cr+i]) {
2101 int dx = j % r, dy = j / r, crm = max(c, r);
2105 str[0] += 'a' - ('9'+1);
2106 draw_text(fe, tx + (4*dx+3) * TILE_SIZE / (4*r+2),
2107 ty + (4*dy+3) * TILE_SIZE / (4*c+2),
2108 FONT_VARIABLE, TILE_SIZE/(crm*5/4),
2109 ALIGN_VCENTRE | ALIGN_HCENTRE, COL_PENCIL, str);
2116 draw_update(fe, cx, cy, cw, ch);
2118 ds->grid[y*cr+x] = state->grid[y*cr+x];
2119 memcpy(ds->pencil+(y*cr+x)*cr, state->pencil+(y*cr+x)*cr, cr);
2120 ds->hl[y*cr+x] = hl;
2123 static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
2124 game_state *state, int dir, game_ui *ui,
2125 float animtime, float flashtime)
2127 int c = state->c, r = state->r, cr = c*r;
2128 int entered_items[cr*cr];
2133 * The initial contents of the window are not guaranteed
2134 * and can vary with front ends. To be on the safe side,
2135 * all games should start by drawing a big
2136 * background-colour rectangle covering the whole window.
2138 draw_rect(fe, 0, 0, XSIZE(cr), YSIZE(cr), COL_BACKGROUND);
2143 for (x = 0; x <= cr; x++) {
2144 int thick = (x % r ? 0 : 1);
2145 draw_rect(fe, BORDER + x*TILE_SIZE - thick, BORDER-1,
2146 1+2*thick, cr*TILE_SIZE+3, COL_GRID);
2148 for (y = 0; y <= cr; y++) {
2149 int thick = (y % c ? 0 : 1);
2150 draw_rect(fe, BORDER-1, BORDER + y*TILE_SIZE - thick,
2151 cr*TILE_SIZE+3, 1+2*thick, COL_GRID);
2156 * This array is used to keep track of rows, columns and boxes
2157 * which contain a number more than once.
2159 for (x = 0; x < cr * cr; x++)
2160 entered_items[x] = 0;
2161 for (x = 0; x < cr; x++)
2162 for (y = 0; y < cr; y++) {
2163 digit d = state->grid[y*cr+x];
2165 int box = (x/r)+(y/c)*c;
2166 entered_items[x*cr+d-1] |= ((entered_items[x*cr+d-1] & 1) << 1) | 1;
2167 entered_items[y*cr+d-1] |= ((entered_items[y*cr+d-1] & 4) << 1) | 4;
2168 entered_items[box*cr+d-1] |= ((entered_items[box*cr+d-1] & 16) << 1) | 16;
2173 * Draw any numbers which need redrawing.
2175 for (x = 0; x < cr; x++) {
2176 for (y = 0; y < cr; y++) {
2178 digit d = state->grid[y*cr+x];
2180 if (flashtime > 0 &&
2181 (flashtime <= FLASH_TIME/3 ||
2182 flashtime >= FLASH_TIME*2/3))
2185 /* Highlight active input areas. */
2186 if (x == ui->hx && y == ui->hy)
2187 highlight = ui->hpencil ? 2 : 1;
2189 /* Mark obvious errors (ie, numbers which occur more than once
2190 * in a single row, column, or box). */
2191 if ((entered_items[x*cr+d-1] & 2) ||
2192 (entered_items[y*cr+d-1] & 8) ||
2193 (entered_items[((x/r)+(y/c)*c)*cr+d-1] & 32))
2196 draw_number(fe, ds, state, x, y, highlight);
2201 * Update the _entire_ grid if necessary.
2204 draw_update(fe, 0, 0, XSIZE(cr), YSIZE(cr));
2209 static float game_anim_length(game_state *oldstate, game_state *newstate,
2210 int dir, game_ui *ui)
2215 static float game_flash_length(game_state *oldstate, game_state *newstate,
2216 int dir, game_ui *ui)
2218 if (!oldstate->completed && newstate->completed &&
2219 !oldstate->cheated && !newstate->cheated)
2224 static int game_wants_statusbar(void)
2229 static int game_timing_state(game_state *state)
2235 #define thegame solo
2238 const struct game thegame = {
2239 "Solo", "games.solo",
2246 TRUE, game_configure, custom_params,
2255 TRUE, game_text_format,
2262 game_free_drawstate,
2266 game_wants_statusbar,
2267 FALSE, game_timing_state,
2268 0, /* mouse_priorities */
2271 #ifdef STANDALONE_SOLVER
2274 * gcc -DSTANDALONE_SOLVER -o solosolver solo.c malloc.c
2277 void frontend_default_colour(frontend *fe, float *output) {}
2278 void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize,
2279 int align, int colour, char *text) {}
2280 void draw_rect(frontend *fe, int x, int y, int w, int h, int colour) {}
2281 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour) {}
2282 void draw_polygon(frontend *fe, int *coords, int npoints,
2283 int fill, int colour) {}
2284 void clip(frontend *fe, int x, int y, int w, int h) {}
2285 void unclip(frontend *fe) {}
2286 void start_draw(frontend *fe) {}
2287 void draw_update(frontend *fe, int x, int y, int w, int h) {}
2288 void end_draw(frontend *fe) {}
2289 unsigned long random_bits(random_state *state, int bits)
2290 { assert(!"Shouldn't get randomness"); return 0; }
2291 unsigned long random_upto(random_state *state, unsigned long limit)
2292 { assert(!"Shouldn't get randomness"); return 0; }
2294 void fatal(char *fmt, ...)
2298 fprintf(stderr, "fatal error: ");
2301 vfprintf(stderr, fmt, ap);
2304 fprintf(stderr, "\n");
2308 int main(int argc, char **argv)
2313 char *id = NULL, *desc, *err;
2317 while (--argc > 0) {
2319 if (!strcmp(p, "-r")) {
2321 } else if (!strcmp(p, "-n")) {
2323 } else if (!strcmp(p, "-v")) {
2324 solver_show_working = TRUE;
2326 } else if (!strcmp(p, "-g")) {
2329 } else if (*p == '-') {
2330 fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0]);
2338 fprintf(stderr, "usage: %s [-n | -r | -g | -v] <game_id>\n", argv[0]);
2342 desc = strchr(id, ':');
2344 fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]);
2349 p = default_params();
2350 decode_params(p, id);
2351 err = validate_desc(p, desc);
2353 fprintf(stderr, "%s: %s\n", argv[0], err);
2356 s = new_game(NULL, p, desc);
2359 int ret = rsolve(p->c, p->r, s->grid, NULL, 2);
2361 fprintf(stderr, "%s: rsolve: multiple solutions detected\n",
2365 int ret = nsolve(p->c, p->r, s->grid);
2367 if (ret == DIFF_IMPOSSIBLE) {
2369 * Now resort to rsolve to determine whether it's
2372 ret = rsolve(p->c, p->r, s->grid, NULL, 2);
2374 ret = DIFF_IMPOSSIBLE;
2376 ret = DIFF_RECURSIVE;
2378 ret = DIFF_AMBIGUOUS;
2380 printf("Difficulty rating: %s\n",
2381 ret==DIFF_BLOCK ? "Trivial (blockwise positional elimination only)":
2382 ret==DIFF_SIMPLE ? "Basic (row/column/number elimination required)":
2383 ret==DIFF_INTERSECT ? "Intermediate (intersectional analysis required)":
2384 ret==DIFF_SET ? "Advanced (set elimination required)":
2385 ret==DIFF_RECURSIVE ? "Unreasonable (guesswork and backtracking required)":
2386 ret==DIFF_AMBIGUOUS ? "Ambiguous (multiple solutions exist)":
2387 ret==DIFF_IMPOSSIBLE ? "Impossible (no solution exists)":
2388 "INTERNAL ERROR: unrecognised difficulty code");
2392 printf("%s\n", grid_text_format(p->c, p->r, s->grid));