--- /dev/null
+/*
+ * solo.c: the number-placing puzzle most popularly known as `Sudoku'.
+ *
+ * TODO:
+ *
+ * - finalise game name
+ *
+ * - can we do anything about nasty centring of text in GTK? It
+ * seems to be taking ascenders/descenders into account when
+ * centring. Ick.
+ *
+ * - implement stronger modes of reasoning in nsolve, thus
+ * enabling harder puzzles
+ *
+ * - configurable difficulty levels
+ *
+ * - vary the symmetry (rotational or none)?
+ *
+ * - try for cleverer ways of reducing the solved grid; they seem
+ * to be coming out a bit full for the most part, and in
+ * particular it's inexcusable to leave a grid with an entire
+ * block (or presumably row or column) filled! I _hope_ we can
+ * do this simply by better prioritising (somehow) the possible
+ * removals.
+ * + one simple option might be to work the other way: start
+ * with an empty grid and gradually _add_ numbers until it
+ * becomes solvable? Perhaps there might be some heuristic
+ * which enables us to pinpoint the most critical clues and
+ * thus add as few as possible.
+ *
+ * - alternative interface modes
+ * + sudoku.com's Windows program has a palette of possible
+ * entries; you select a palette entry first and then click
+ * on the square you want it to go in, thus enabling
+ * mouse-only play. Useful for PDAs! I don't think it's
+ * actually incompatible with the current highlight-then-type
+ * approach: you _either_ highlight a palette entry and then
+ * click, _or_ you highlight a square and then type. At most
+ * one thing is ever highlighted at a time, so there's no way
+ * to confuse the two.
+ * + `pencil marks' might be useful for more subtle forms of
+ * deduction, once we implement creation of puzzles that
+ * require it.
+ */
+
+/*
+ * Solo puzzles need to be square overall (since each row and each
+ * column must contain one of every digit), but they need not be
+ * subdivided the same way internally. I am going to adopt a
+ * convention whereby I _always_ refer to `r' as the number of rows
+ * of _big_ divisions, and `c' as the number of columns of _big_
+ * divisions. Thus, a 2c by 3r puzzle looks something like this:
+ *
+ * 4 5 1 | 2 6 3
+ * 6 3 2 | 5 4 1
+ * ------+------ (Of course, you can't subdivide it the other way
+ * 1 4 5 | 6 3 2 or you'll get clashes; observe that the 4 in the
+ * 3 2 6 | 4 1 5 top left would conflict with the 4 in the second
+ * ------+------ box down on the left-hand side.)
+ * 5 1 4 | 3 2 6
+ * 2 6 3 | 1 5 4
+ *
+ * The need for a strong naming convention should now be clear:
+ * each small box is two rows of digits by three columns, while the
+ * overall puzzle has three rows of small boxes by two columns. So
+ * I will (hopefully) consistently use `r' to denote the number of
+ * rows _of small boxes_ (here 3), which is also the number of
+ * columns of digits in each small box; and `c' vice versa (here
+ * 2).
+ *
+ * I'm also going to choose arbitrarily to list c first wherever
+ * possible: the above is a 2x3 puzzle, not a 3x2 one.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <ctype.h>
+#include <math.h>
+
+#include "puzzles.h"
+
+/*
+ * To save space, I store digits internally as unsigned char. This
+ * imposes a hard limit of 255 on the order of the puzzle. Since
+ * even a 5x5 takes unacceptably long to generate, I don't see this
+ * as a serious limitation unless something _really_ impressive
+ * happens in computing technology; but here's a typedef anyway for
+ * general good practice.
+ */
+typedef unsigned char digit;
+#define ORDER_MAX 255
+
+#define TILE_SIZE 32
+#define BORDER 18
+
+#define FLASH_TIME 0.4F
+
+enum {
+ COL_BACKGROUND,
+ COL_GRID,
+ COL_CLUE,
+ COL_USER,
+ COL_HIGHLIGHT,
+ NCOLOURS
+};
+
+struct game_params {
+ int c, r;
+};
+
+struct game_state {
+ int c, r;
+ digit *grid;
+ unsigned char *immutable; /* marks which digits are clues */
+ int completed;
+};
+
+static game_params *default_params(void)
+{
+ game_params *ret = snew(game_params);
+
+ ret->c = ret->r = 3;
+
+ return ret;
+}
+
+static int game_fetch_preset(int i, char **name, game_params **params)
+{
+ game_params *ret;
+ int c, r;
+ char buf[80];
+
+ switch (i) {
+ case 0: c = 2, r = 2; break;
+ case 1: c = 2, r = 3; break;
+ case 2: c = 3, r = 3; break;
+ case 3: c = 3, r = 4; break;
+ case 4: c = 4, r = 4; break;
+ default: return FALSE;
+ }
+
+ sprintf(buf, "%dx%d", c, r);
+ *name = dupstr(buf);
+ *params = ret = snew(game_params);
+ ret->c = c;
+ ret->r = r;
+ /* FIXME: difficulty presets? */
+ return TRUE;
+}
+
+static void free_params(game_params *params)
+{
+ sfree(params);
+}
+
+static game_params *dup_params(game_params *params)
+{
+ game_params *ret = snew(game_params);
+ *ret = *params; /* structure copy */
+ return ret;
+}
+
+static game_params *decode_params(char const *string)
+{
+ game_params *ret = default_params();
+
+ ret->c = ret->r = atoi(string);
+ while (*string && isdigit((unsigned char)*string)) string++;
+ if (*string == 'x') {
+ string++;
+ ret->r = atoi(string);
+ while (*string && isdigit((unsigned char)*string)) string++;
+ }
+ /* FIXME: difficulty levels */
+
+ return ret;
+}
+
+static char *encode_params(game_params *params)
+{
+ char str[80];
+
+ sprintf(str, "%dx%d", params->c, params->r);
+ return dupstr(str);
+}
+
+static config_item *game_configure(game_params *params)
+{
+ config_item *ret;
+ char buf[80];
+
+ ret = snewn(5, config_item);
+
+ ret[0].name = "Columns of sub-blocks";
+ ret[0].type = C_STRING;
+ sprintf(buf, "%d", params->c);
+ ret[0].sval = dupstr(buf);
+ ret[0].ival = 0;
+
+ ret[1].name = "Rows of sub-blocks";
+ ret[1].type = C_STRING;
+ sprintf(buf, "%d", params->r);
+ ret[1].sval = dupstr(buf);
+ ret[1].ival = 0;
+
+ /*
+ * FIXME: difficulty level.
+ */
+
+ ret[2].name = NULL;
+ ret[2].type = C_END;
+ ret[2].sval = NULL;
+ ret[2].ival = 0;
+
+ return ret;
+}
+
+static game_params *custom_params(config_item *cfg)
+{
+ game_params *ret = snew(game_params);
+
+ ret->c = atof(cfg[0].sval);
+ ret->r = atof(cfg[1].sval);
+
+ return ret;
+}
+
+static char *validate_params(game_params *params)
+{
+ if (params->c < 2 || params->r < 2)
+ return "Both dimensions must be at least 2";
+ if (params->c > ORDER_MAX || params->r > ORDER_MAX)
+ return "Dimensions greater than "STR(ORDER_MAX)" are not supported";
+ return NULL;
+}
+
+/* ----------------------------------------------------------------------
+ * Full recursive Solo solver.
+ *
+ * The algorithm for this solver is shamelessly copied from a
+ * Python solver written by Andrew Wilkinson (which is GPLed, but
+ * I've reused only ideas and no code). It mostly just does the
+ * obvious recursive thing: pick an empty square, put one of the
+ * possible digits in it, recurse until all squares are filled,
+ * backtrack and change some choices if necessary.
+ *
+ * The clever bit is that every time it chooses which square to
+ * fill in next, it does so by counting the number of _possible_
+ * numbers that can go in each square, and it prioritises so that
+ * it picks a square with the _lowest_ number of possibilities. The
+ * idea is that filling in lots of the obvious bits (particularly
+ * any squares with only one possibility) will cut down on the list
+ * of possibilities for other squares and hence reduce the enormous
+ * search space as much as possible as early as possible.
+ *
+ * In practice the algorithm appeared to work very well; run on
+ * sample problems from the Times it completed in well under a
+ * second on my G5 even when written in Python, and given an empty
+ * grid (so that in principle it would enumerate _all_ solved
+ * grids!) it found the first valid solution just as quickly. So
+ * with a bit more randomisation I see no reason not to use this as
+ * my grid generator.
+ */
+
+/*
+ * Internal data structure used in solver to keep track of
+ * progress.
+ */
+struct rsolve_coord { int x, y, r; };
+struct rsolve_usage {
+ int c, r, cr; /* cr == c*r */
+ /* grid is a copy of the input grid, modified as we go along */
+ digit *grid;
+ /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
+ unsigned char *row;
+ /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
+ unsigned char *col;
+ /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
+ unsigned char *blk;
+ /* This lists all the empty spaces remaining in the grid. */
+ struct rsolve_coord *spaces;
+ int nspaces;
+ /* If we need randomisation in the solve, this is our random state. */
+ random_state *rs;
+ /* Number of solutions so far found, and maximum number we care about. */
+ int solns, maxsolns;
+};
+
+/*
+ * The real recursive step in the solving function.
+ */
+static void rsolve_real(struct rsolve_usage *usage, digit *grid)
+{
+ int c = usage->c, r = usage->r, cr = usage->cr;
+ int i, j, n, sx, sy, bestm, bestr;
+ int *digits;
+
+ /*
+ * Firstly, check for completion! If there are no spaces left
+ * in the grid, we have a solution.
+ */
+ if (usage->nspaces == 0) {
+ if (!usage->solns) {
+ /*
+ * This is our first solution, so fill in the output grid.
+ */
+ memcpy(grid, usage->grid, cr * cr);
+ }
+ usage->solns++;
+ return;
+ }
+
+ /*
+ * Otherwise, there must be at least one space. Find the most
+ * constrained space, using the `r' field as a tie-breaker.
+ */
+ bestm = cr+1; /* so that any space will beat it */
+ bestr = 0;
+ i = sx = sy = -1;
+ for (j = 0; j < usage->nspaces; j++) {
+ int x = usage->spaces[j].x, y = usage->spaces[j].y;
+ int m;
+
+ /*
+ * Find the number of digits that could go in this space.
+ */
+ m = 0;
+ for (n = 0; n < cr; n++)
+ if (!usage->row[y*cr+n] && !usage->col[x*cr+n] &&
+ !usage->blk[((y/c)*c+(x/r))*cr+n])
+ m++;
+
+ if (m < bestm || (m == bestm && usage->spaces[j].r < bestr)) {
+ bestm = m;
+ bestr = usage->spaces[j].r;
+ sx = x;
+ sy = y;
+ i = j;
+ }
+ }
+
+ /*
+ * Swap that square into the final place in the spaces array,
+ * so that decrementing nspaces will remove it from the list.
+ */
+ if (i != usage->nspaces-1) {
+ struct rsolve_coord t;
+ t = usage->spaces[usage->nspaces-1];
+ usage->spaces[usage->nspaces-1] = usage->spaces[i];
+ usage->spaces[i] = t;
+ }
+
+ /*
+ * Now we've decided which square to start our recursion at,
+ * simply go through all possible values, shuffling them
+ * randomly first if necessary.
+ */
+ digits = snewn(bestm, int);
+ j = 0;
+ for (n = 0; n < cr; n++)
+ if (!usage->row[sy*cr+n] && !usage->col[sx*cr+n] &&
+ !usage->blk[((sy/c)*c+(sx/r))*cr+n]) {
+ digits[j++] = n+1;
+ }
+
+ if (usage->rs) {
+ /* shuffle */
+ for (i = j; i > 1; i--) {
+ int p = random_upto(usage->rs, i);
+ if (p != i-1) {
+ int t = digits[p];
+ digits[p] = digits[i-1];
+ digits[i-1] = t;
+ }
+ }
+ }
+
+ /* And finally, go through the digit list and actually recurse. */
+ for (i = 0; i < j; i++) {
+ n = digits[i];
+
+ /* Update the usage structure to reflect the placing of this digit. */
+ usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] =
+ usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = TRUE;
+ usage->grid[sy*cr+sx] = n;
+ usage->nspaces--;
+
+ /* Call the solver recursively. */
+ rsolve_real(usage, grid);
+
+ /*
+ * If we have seen as many solutions as we need, terminate
+ * all processing immediately.
+ */
+ if (usage->solns >= usage->maxsolns)
+ break;
+
+ /* Revert the usage structure. */
+ usage->row[sy*cr+n-1] = usage->col[sx*cr+n-1] =
+ usage->blk[((sy/c)*c+(sx/r))*cr+n-1] = FALSE;
+ usage->grid[sy*cr+sx] = 0;
+ usage->nspaces++;
+ }
+
+ sfree(digits);
+}
+
+/*
+ * Entry point to solver. You give it dimensions and a starting
+ * grid, which is simply an array of N^4 digits. In that array, 0
+ * means an empty square, and 1..N mean a clue square.
+ *
+ * Return value is the number of solutions found; searching will
+ * stop after the provided `max'. (Thus, you can pass max==1 to
+ * indicate that you only care about finding _one_ solution, or
+ * max==2 to indicate that you want to know the difference between
+ * a unique and non-unique solution.) The input parameter `grid' is
+ * also filled in with the _first_ (or only) solution found by the
+ * solver.
+ */
+static int rsolve(int c, int r, digit *grid, random_state *rs, int max)
+{
+ struct rsolve_usage *usage;
+ int x, y, cr = c*r;
+ int ret;
+
+ /*
+ * Create an rsolve_usage structure.
+ */
+ usage = snew(struct rsolve_usage);
+
+ usage->c = c;
+ usage->r = r;
+ usage->cr = cr;
+
+ usage->grid = snewn(cr * cr, digit);
+ memcpy(usage->grid, grid, cr * cr);
+
+ usage->row = snewn(cr * cr, unsigned char);
+ usage->col = snewn(cr * cr, unsigned char);
+ usage->blk = snewn(cr * cr, unsigned char);
+ memset(usage->row, FALSE, cr * cr);
+ memset(usage->col, FALSE, cr * cr);
+ memset(usage->blk, FALSE, cr * cr);
+
+ usage->spaces = snewn(cr * cr, struct rsolve_coord);
+ usage->nspaces = 0;
+
+ usage->solns = 0;
+ usage->maxsolns = max;
+
+ usage->rs = rs;
+
+ /*
+ * Now fill it in with data from the input grid.
+ */
+ for (y = 0; y < cr; y++) {
+ for (x = 0; x < cr; x++) {
+ int v = grid[y*cr+x];
+ if (v == 0) {
+ usage->spaces[usage->nspaces].x = x;
+ usage->spaces[usage->nspaces].y = y;
+ if (rs)
+ usage->spaces[usage->nspaces].r = random_bits(rs, 31);
+ else
+ usage->spaces[usage->nspaces].r = usage->nspaces;
+ usage->nspaces++;
+ } else {
+ usage->row[y*cr+v-1] = TRUE;
+ usage->col[x*cr+v-1] = TRUE;
+ usage->blk[((y/c)*c+(x/r))*cr+v-1] = TRUE;
+ }
+ }
+ }
+
+ /*
+ * Run the real recursive solving function.
+ */
+ rsolve_real(usage, grid);
+ ret = usage->solns;
+
+ /*
+ * Clean up the usage structure now we have our answer.
+ */
+ sfree(usage->spaces);
+ sfree(usage->blk);
+ sfree(usage->col);
+ sfree(usage->row);
+ sfree(usage->grid);
+ sfree(usage);
+
+ /*
+ * And return.
+ */
+ return ret;
+}
+
+/* ----------------------------------------------------------------------
+ * End of recursive solver code.
+ */
+
+/* ----------------------------------------------------------------------
+ * Less capable non-recursive solver. This one is used to check
+ * solubility of a grid as we gradually remove numbers from it: by
+ * verifying a grid using this solver we can ensure it isn't _too_
+ * hard (e.g. does not actually require guessing and backtracking).
+ *
+ * It supports a variety of specific modes of reasoning. By
+ * enabling or disabling subsets of these modes we can arrange a
+ * range of difficulty levels.
+ */
+
+/*
+ * Modes of reasoning currently supported:
+ *
+ * - Positional elimination: a number must go in a particular
+ * square because all the other empty squares in a given
+ * row/col/blk are ruled out.
+ *
+ * - Numeric elimination: a square must have a particular number
+ * in because all the other numbers that could go in it are
+ * ruled out.
+ *
+ * More advanced modes of reasoning I'd like to support in future:
+ *
+ * - Intersectional elimination: given two domains which overlap
+ * (hence one must be a block, and the other can be a row or
+ * col), if the possible locations for a particular number in
+ * one of the domains can be narrowed down to the overlap, then
+ * that number can be ruled out everywhere but the overlap in
+ * the other domain too.
+ *
+ * - Setwise numeric elimination: if there is a subset of the
+ * empty squares within a domain such that the union of the
+ * possible numbers in that subset has the same size as the
+ * subset itself, then those numbers can be ruled out everywhere
+ * else in the domain. (For example, if there are five empty
+ * squares and the possible numbers in each are 12, 23, 13, 134
+ * and 1345, then the first three empty squares form such a
+ * subset: the numbers 1, 2 and 3 _must_ be in those three
+ * squares in some permutation, and hence we can deduce none of
+ * them can be in the fourth or fifth squares.)
+ */
+
+struct nsolve_usage {
+ int c, r, cr;
+ /*
+ * We set up a cubic array, indexed by x, y and digit; each
+ * element of this array is TRUE or FALSE according to whether
+ * or not that digit _could_ in principle go in that position.
+ *
+ * The way to index this array is cube[(x*cr+y)*cr+n-1].
+ */
+ unsigned char *cube;
+ /*
+ * This is the grid in which we write down our final
+ * deductions.
+ */
+ digit *grid;
+ /*
+ * Now we keep track, at a slightly higher level, of what we
+ * have yet to work out, to prevent doing the same deduction
+ * many times.
+ */
+ /* row[y*cr+n-1] TRUE if digit n has been placed in row y */
+ unsigned char *row;
+ /* col[x*cr+n-1] TRUE if digit n has been placed in row x */
+ unsigned char *col;
+ /* blk[(y*c+x)*cr+n-1] TRUE if digit n has been placed in block (x,y) */
+ unsigned char *blk;
+};
+#define cube(x,y,n) (usage->cube[((x)*usage->cr+(y))*usage->cr+(n)-1])
+
+/*
+ * Function called when we are certain that a particular square has
+ * a particular number in it.
+ */
+static void nsolve_place(struct nsolve_usage *usage, int x, int y, int n)
+{
+ int c = usage->c, r = usage->r, cr = usage->cr;
+ int i, j, bx, by;
+
+ assert(cube(x,y,n));
+
+ /*
+ * Rule out all other numbers in this square.
+ */
+ for (i = 1; i <= cr; i++)
+ if (i != n)
+ cube(x,y,i) = FALSE;
+
+ /*
+ * Rule out this number in all other positions in the row.
+ */
+ for (i = 0; i < cr; i++)
+ if (i != y)
+ cube(x,i,n) = FALSE;
+
+ /*
+ * Rule out this number in all other positions in the column.
+ */
+ for (i = 0; i < cr; i++)
+ if (i != x)
+ cube(i,y,n) = FALSE;
+
+ /*
+ * Rule out this number in all other positions in the block.
+ */
+ bx = (x/r)*r;
+ by = (y/c)*c;
+ for (i = 0; i < r; i++)
+ for (j = 0; j < c; j++)
+ if (bx+i != x || by+j != y)
+ cube(bx+i,by+j,n) = FALSE;
+
+ /*
+ * Enter the number in the result grid.
+ */
+ usage->grid[y*cr+x] = n;
+
+ /*
+ * Cross out this number from the list of numbers left to place
+ * in its row, its column and its block.
+ */
+ usage->row[y*cr+n-1] = usage->col[x*cr+n-1] =
+ usage->blk[((y/c)*c+(x/r))*cr+n-1] = TRUE;
+}
+
+static int nsolve_blk_pos_elim(struct nsolve_usage *usage,
+ int x, int y, int n)
+{
+ int c = usage->c, r = usage->r;
+ int i, j, fx, fy, m;
+
+ x *= r;
+ y *= c;
+
+ /*
+ * Count the possible positions within this block where this
+ * number could appear.
+ */
+ m = 0;
+ fx = fy = -1;
+ for (i = 0; i < r; i++)
+ for (j = 0; j < c; j++)
+ if (cube(x+i,y+j,n)) {
+ fx = x+i;
+ fy = y+j;
+ m++;
+ }
+
+ if (m == 1) {
+ assert(fx >= 0 && fy >= 0);
+ nsolve_place(usage, fx, fy, n);
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+static int nsolve_row_pos_elim(struct nsolve_usage *usage,
+ int y, int n)
+{
+ int cr = usage->cr;
+ int x, fx, m;
+
+ /*
+ * Count the possible positions within this row where this
+ * number could appear.
+ */
+ m = 0;
+ fx = -1;
+ for (x = 0; x < cr; x++)
+ if (cube(x,y,n)) {
+ fx = x;
+ m++;
+ }
+
+ if (m == 1) {
+ assert(fx >= 0);
+ nsolve_place(usage, fx, y, n);
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+static int nsolve_col_pos_elim(struct nsolve_usage *usage,
+ int x, int n)
+{
+ int cr = usage->cr;
+ int y, fy, m;
+
+ /*
+ * Count the possible positions within this column where this
+ * number could appear.
+ */
+ m = 0;
+ fy = -1;
+ for (y = 0; y < cr; y++)
+ if (cube(x,y,n)) {
+ fy = y;
+ m++;
+ }
+
+ if (m == 1) {
+ assert(fy >= 0);
+ nsolve_place(usage, x, fy, n);
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+static int nsolve_num_elim(struct nsolve_usage *usage,
+ int x, int y)
+{
+ int cr = usage->cr;
+ int n, fn, m;
+
+ /*
+ * Count the possible numbers that could appear in this square.
+ */
+ m = 0;
+ fn = -1;
+ for (n = 1; n <= cr; n++)
+ if (cube(x,y,n)) {
+ fn = n;
+ m++;
+ }
+
+ if (m == 1) {
+ assert(fn > 0);
+ nsolve_place(usage, x, y, fn);
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+static int nsolve(int c, int r, digit *grid)
+{
+ struct nsolve_usage *usage;
+ int cr = c*r;
+ int x, y, n;
+
+ /*
+ * Set up a usage structure as a clean slate (everything
+ * possible).
+ */
+ usage = snew(struct nsolve_usage);
+ usage->c = c;
+ usage->r = r;
+ usage->cr = cr;
+ usage->cube = snewn(cr*cr*cr, unsigned char);
+ usage->grid = grid; /* write straight back to the input */
+ memset(usage->cube, TRUE, cr*cr*cr);
+
+ usage->row = snewn(cr * cr, unsigned char);
+ usage->col = snewn(cr * cr, unsigned char);
+ usage->blk = snewn(cr * cr, unsigned char);
+ memset(usage->row, FALSE, cr * cr);
+ memset(usage->col, FALSE, cr * cr);
+ memset(usage->blk, FALSE, cr * cr);
+
+ /*
+ * Place all the clue numbers we are given.
+ */
+ for (x = 0; x < cr; x++)
+ for (y = 0; y < cr; y++)
+ if (grid[y*cr+x])
+ nsolve_place(usage, x, y, grid[y*cr+x]);
+
+ /*
+ * Now loop over the grid repeatedly trying all permitted modes
+ * of reasoning. The loop terminates if we complete an
+ * iteration without making any progress; we then return
+ * failure or success depending on whether the grid is full or
+ * not.
+ */
+ while (1) {
+ /*
+ * Blockwise positional elimination.
+ */
+ for (x = 0; x < c; x++)
+ for (y = 0; y < r; y++)
+ for (n = 1; n <= cr; n++)
+ if (!usage->blk[((y/c)*c+(x/r))*cr+n-1] &&
+ nsolve_blk_pos_elim(usage, x, y, n))
+ continue;
+
+ /*
+ * Row-wise positional elimination.
+ */
+ for (y = 0; y < cr; y++)
+ for (n = 1; n <= cr; n++)
+ if (!usage->row[y*cr+n-1] &&
+ nsolve_row_pos_elim(usage, y, n))
+ continue;
+ /*
+ * Column-wise positional elimination.
+ */
+ for (x = 0; x < cr; x++)
+ for (n = 1; n <= cr; n++)
+ if (!usage->col[x*cr+n-1] &&
+ nsolve_col_pos_elim(usage, x, n))
+ continue;
+
+ /*
+ * Numeric elimination.
+ */
+ for (x = 0; x < cr; x++)
+ for (y = 0; y < cr; y++)
+ if (!usage->grid[y*cr+x] &&
+ nsolve_num_elim(usage, x, y))
+ continue;
+
+ /*
+ * If we reach here, we have made no deductions in this
+ * iteration, so the algorithm terminates.
+ */
+ break;
+ }
+
+ sfree(usage->cube);
+ sfree(usage->row);
+ sfree(usage->col);
+ sfree(usage->blk);
+ sfree(usage);
+
+ for (x = 0; x < cr; x++)
+ for (y = 0; y < cr; y++)
+ if (!grid[y*cr+x])
+ return FALSE;
+ return TRUE;
+}
+
+/* ----------------------------------------------------------------------
+ * End of non-recursive solver code.
+ */
+
+/*
+ * Check whether a grid contains a valid complete puzzle.
+ */
+static int check_valid(int c, int r, digit *grid)
+{
+ int cr = c*r;
+ unsigned char *used;
+ int x, y, n;
+
+ used = snewn(cr, unsigned char);
+
+ /*
+ * Check that each row contains precisely one of everything.
+ */
+ for (y = 0; y < cr; y++) {
+ memset(used, FALSE, cr);
+ for (x = 0; x < cr; x++)
+ if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr)
+ used[grid[y*cr+x]-1] = TRUE;
+ for (n = 0; n < cr; n++)
+ if (!used[n]) {
+ sfree(used);
+ return FALSE;
+ }
+ }
+
+ /*
+ * Check that each column contains precisely one of everything.
+ */
+ for (x = 0; x < cr; x++) {
+ memset(used, FALSE, cr);
+ for (y = 0; y < cr; y++)
+ if (grid[y*cr+x] > 0 && grid[y*cr+x] <= cr)
+ used[grid[y*cr+x]-1] = TRUE;
+ for (n = 0; n < cr; n++)
+ if (!used[n]) {
+ sfree(used);
+ return FALSE;
+ }
+ }
+
+ /*
+ * Check that each block contains precisely one of everything.
+ */
+ for (x = 0; x < cr; x += r) {
+ for (y = 0; y < cr; y += c) {
+ int xx, yy;
+ memset(used, FALSE, cr);
+ for (xx = x; xx < x+r; xx++)
+ for (yy = 0; yy < y+c; yy++)
+ if (grid[yy*cr+xx] > 0 && grid[yy*cr+xx] <= cr)
+ used[grid[yy*cr+xx]-1] = TRUE;
+ for (n = 0; n < cr; n++)
+ if (!used[n]) {
+ sfree(used);
+ return FALSE;
+ }
+ }
+ }
+
+ sfree(used);
+ return TRUE;
+}
+
+static char *new_game_seed(game_params *params, random_state *rs)
+{
+ int c = params->c, r = params->r, cr = c*r;
+ int area = cr*cr;
+ digit *grid, *grid2;
+ struct xy { int x, y; } *locs;
+ int nlocs;
+ int ret;
+ char *seed;
+
+ /*
+ * Start the recursive solver with an empty grid to generate a
+ * random solved state.
+ */
+ grid = snewn(area, digit);
+ memset(grid, 0, area);
+ ret = rsolve(c, r, grid, rs, 1);
+ assert(ret == 1);
+ assert(check_valid(c, r, grid));
+
+#ifdef DEBUG
+ memcpy(grid,
+ "\x0\x1\x0\x0\x6\x0\x0\x0\x0"
+ "\x5\x0\x0\x7\x0\x4\x0\x2\x0"
+ "\x0\x0\x6\x1\x0\x0\x0\x0\x0"
+ "\x8\x9\x7\x0\x0\x0\x0\x0\x0"
+ "\x0\x0\x3\x0\x4\x0\x9\x0\x0"
+ "\x0\x0\x0\x0\x0\x0\x8\x7\x6"
+ "\x0\x0\x0\x0\x0\x9\x1\x0\x0"
+ "\x0\x3\x0\x6\x0\x5\x0\x0\x7"
+ "\x0\x0\x0\x0\x8\x0\x0\x5\x0"
+ , area);
+
+ {
+ int y, x;
+ for (y = 0; y < cr; y++) {
+ for (x = 0; x < cr; x++) {
+ printf("%2.0d", grid[y*cr+x]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+ }
+
+ nsolve(c, r, grid);
+
+ {
+ int y, x;
+ for (y = 0; y < cr; y++) {
+ for (x = 0; x < cr; x++) {
+ printf("%2.0d", grid[y*cr+x]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+ }
+#endif
+
+ /*
+ * Now we have a solved grid, start removing things from it
+ * while preserving solubility.
+ */
+ locs = snewn((cr+1)/2 * (cr+1)/2, struct xy);
+ grid2 = snewn(area, digit);
+ while (1) {
+ int x, y, i;
+
+ /*
+ * Iterate over the top left corner of the grid and
+ * enumerate all the filled squares we could empty.
+ */
+ nlocs = 0;
+
+ for (x = 0; 2*x < cr; x++)
+ for (y = 0; 2*y < cr; y++)
+ if (grid[y*cr+x]) {
+ locs[nlocs].x = x;
+ locs[nlocs].y = y;
+ nlocs++;
+ }
+
+ /*
+ * Now shuffle that list.
+ */
+ for (i = nlocs; i > 1; i--) {
+ int p = random_upto(rs, i);
+ if (p != i-1) {
+ struct xy t = locs[p];
+ locs[p] = locs[i-1];
+ locs[i-1] = t;
+ }
+ }
+
+ /*
+ * Now loop over the shuffled list and, for each element,
+ * see whether removing that element (and its reflections)
+ * from the grid will still leave the grid soluble by
+ * nsolve.
+ */
+ for (i = 0; i < nlocs; i++) {
+ x = locs[i].x;
+ y = locs[i].y;
+
+ memcpy(grid2, grid, area);
+ grid2[y*cr+x] = 0;
+ grid2[y*cr+cr-1-x] = 0;
+ grid2[(cr-1-y)*cr+x] = 0;
+ grid2[(cr-1-y)*cr+cr-1-x] = 0;
+
+ if (nsolve(c, r, grid2)) {
+ grid[y*cr+x] = 0;
+ grid[y*cr+cr-1-x] = 0;
+ grid[(cr-1-y)*cr+x] = 0;
+ grid[(cr-1-y)*cr+cr-1-x] = 0;
+ break;
+ }
+ }
+
+ if (i == nlocs) {
+ /*
+ * There was nothing we could remove without destroying
+ * solvability.
+ */
+ break;
+ }
+ }
+ sfree(grid2);
+ sfree(locs);
+
+#ifdef DEBUG
+ {
+ int y, x;
+ for (y = 0; y < cr; y++) {
+ for (x = 0; x < cr; x++) {
+ printf("%2.0d", grid[y*cr+x]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+ }
+#endif
+
+ /*
+ * Now we have the grid as it will be presented to the user.
+ * Encode it in a game seed.
+ */
+ {
+ char *p;
+ int run, i;
+
+ seed = snewn(5 * area, char);
+ p = seed;
+ run = 0;
+ for (i = 0; i <= area; i++) {
+ int n = (i < area ? grid[i] : -1);
+
+ if (!n)
+ run++;
+ else {
+ if (run) {
+ while (run > 0) {
+ int c = 'a' - 1 + run;
+ if (run > 26)
+ c = 'z';
+ *p++ = c;
+ run -= c - ('a' - 1);
+ }
+ } else {
+ /*
+ * If there's a number in the very top left or
+ * bottom right, there's no point putting an
+ * unnecessary _ before or after it.
+ */
+ if (p > seed && n > 0)
+ *p++ = '_';
+ }
+ if (n > 0)
+ p += sprintf(p, "%d", n);
+ run = 0;
+ }
+ }
+ assert(p - seed < 5 * area);
+ *p++ = '\0';
+ seed = sresize(seed, p - seed, char);
+ }
+
+ sfree(grid);
+
+ return seed;
+}
+
+static char *validate_seed(game_params *params, char *seed)
+{
+ int area = params->r * params->r * params->c * params->c;
+ int squares = 0;
+
+ while (*seed) {
+ int n = *seed++;
+ if (n >= 'a' && n <= 'z') {
+ squares += n - 'a' + 1;
+ } else if (n == '_') {
+ /* do nothing */;
+ } else if (n > '0' && n <= '9') {
+ squares++;
+ while (*seed >= '0' && *seed <= '9')
+ seed++;
+ } else
+ return "Invalid character in game specification";
+ }
+
+ if (squares < area)
+ return "Not enough data to fill grid";
+
+ if (squares > area)
+ return "Too much data to fit in grid";
+
+ return NULL;
+}
+
+static game_state *new_game(game_params *params, char *seed)
+{
+ game_state *state = snew(game_state);
+ int c = params->c, r = params->r, cr = c*r, area = cr * cr;
+ int i;
+
+ state->c = params->c;
+ state->r = params->r;
+
+ state->grid = snewn(area, digit);
+ state->immutable = snewn(area, unsigned char);
+ memset(state->immutable, FALSE, area);
+
+ state->completed = FALSE;
+
+ i = 0;
+ while (*seed) {
+ int n = *seed++;
+ if (n >= 'a' && n <= 'z') {
+ int run = n - 'a' + 1;
+ assert(i + run <= area);
+ while (run-- > 0)
+ state->grid[i++] = 0;
+ } else if (n == '_') {
+ /* do nothing */;
+ } else if (n > '0' && n <= '9') {
+ assert(i < area);
+ state->immutable[i] = TRUE;
+ state->grid[i++] = atoi(seed-1);
+ while (*seed >= '0' && *seed <= '9')
+ seed++;
+ } else {
+ assert(!"We can't get here");
+ }
+ }
+ assert(i == area);
+
+ return state;
+}
+
+static game_state *dup_game(game_state *state)
+{
+ game_state *ret = snew(game_state);
+ int c = state->c, r = state->r, cr = c*r, area = cr * cr;
+
+ ret->c = state->c;
+ ret->r = state->r;
+
+ ret->grid = snewn(area, digit);
+ memcpy(ret->grid, state->grid, area);
+
+ ret->immutable = snewn(area, unsigned char);
+ memcpy(ret->immutable, state->immutable, area);
+
+ ret->completed = state->completed;
+
+ return ret;
+}
+
+static void free_game(game_state *state)
+{
+ sfree(state->immutable);
+ sfree(state->grid);
+ sfree(state);
+}
+
+struct game_ui {
+ /*
+ * These are the coordinates of the currently highlighted
+ * square on the grid, or -1,-1 if there isn't one. When there
+ * is, pressing a valid number or letter key or Space will
+ * enter that number or letter in the grid.
+ */
+ int hx, hy;
+};
+
+static game_ui *new_ui(game_state *state)
+{
+ game_ui *ui = snew(game_ui);
+
+ ui->hx = ui->hy = -1;
+
+ return ui;
+}
+
+static void free_ui(game_ui *ui)
+{
+ sfree(ui);
+}
+
+static game_state *make_move(game_state *from, game_ui *ui, int x, int y,
+ int button)
+{
+ int c = from->c, r = from->r, cr = c*r;
+ int tx, ty;
+ game_state *ret;
+
+ tx = (x - BORDER) / TILE_SIZE;
+ ty = (y - BORDER) / TILE_SIZE;
+
+ if (tx >= 0 && tx < cr && ty >= 0 && ty < cr && button == LEFT_BUTTON) {
+ if (tx == ui->hx && ty == ui->hy) {
+ ui->hx = ui->hy = -1;
+ } else {
+ ui->hx = tx;
+ ui->hy = ty;
+ }
+ return from; /* UI activity occurred */
+ }
+
+ if (ui->hx != -1 && ui->hy != -1 &&
+ ((button >= '1' && button <= '9' && button - '0' <= cr) ||
+ (button >= 'a' && button <= 'z' && button - 'a' + 10 <= cr) ||
+ (button >= 'A' && button <= 'Z' && button - 'A' + 10 <= cr) ||
+ button == ' ')) {
+ int n = button - '0';
+ if (button >= 'A' && button <= 'Z')
+ n = button - 'A' + 10;
+ if (button >= 'a' && button <= 'z')
+ n = button - 'a' + 10;
+ if (button == ' ')
+ n = 0;
+
+ if (from->immutable[ui->hy*cr+ui->hx])
+ return NULL; /* can't overwrite this square */
+
+ ret = dup_game(from);
+ ret->grid[ui->hy*cr+ui->hx] = n;
+ ui->hx = ui->hy = -1;
+
+ /*
+ * We've made a real change to the grid. Check to see
+ * if the game has been completed.
+ */
+ if (!ret->completed && check_valid(c, r, ret->grid)) {
+ ret->completed = TRUE;
+ }
+
+ return ret; /* made a valid move */
+ }
+
+ return NULL;
+}
+
+/* ----------------------------------------------------------------------
+ * Drawing routines.
+ */
+
+struct game_drawstate {
+ int started;
+ int c, r, cr;
+ digit *grid;
+ unsigned char *hl;
+};
+
+#define XSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
+#define YSIZE(cr) ((cr) * TILE_SIZE + 2*BORDER + 1)
+
+static void game_size(game_params *params, int *x, int *y)
+{
+ int c = params->c, r = params->r, cr = c*r;
+
+ *x = XSIZE(cr);
+ *y = YSIZE(cr);
+}
+
+static float *game_colours(frontend *fe, game_state *state, int *ncolours)
+{
+ float *ret = snewn(3 * NCOLOURS, float);
+
+ frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
+
+ ret[COL_GRID * 3 + 0] = 0.0F;
+ ret[COL_GRID * 3 + 1] = 0.0F;
+ ret[COL_GRID * 3 + 2] = 0.0F;
+
+ ret[COL_CLUE * 3 + 0] = 0.0F;
+ ret[COL_CLUE * 3 + 1] = 0.0F;
+ ret[COL_CLUE * 3 + 2] = 0.0F;
+
+ ret[COL_USER * 3 + 0] = 0.0F;
+ ret[COL_USER * 3 + 1] = 0.6F * ret[COL_BACKGROUND * 3 + 1];
+ ret[COL_USER * 3 + 2] = 0.0F;
+
+ ret[COL_HIGHLIGHT * 3 + 0] = 0.85F * ret[COL_BACKGROUND * 3 + 0];
+ ret[COL_HIGHLIGHT * 3 + 1] = 0.85F * ret[COL_BACKGROUND * 3 + 1];
+ ret[COL_HIGHLIGHT * 3 + 2] = 0.85F * ret[COL_BACKGROUND * 3 + 2];
+
+ *ncolours = NCOLOURS;
+ return ret;
+}
+
+static game_drawstate *game_new_drawstate(game_state *state)
+{
+ struct game_drawstate *ds = snew(struct game_drawstate);
+ int c = state->c, r = state->r, cr = c*r;
+
+ ds->started = FALSE;
+ ds->c = c;
+ ds->r = r;
+ ds->cr = cr;
+ ds->grid = snewn(cr*cr, digit);
+ memset(ds->grid, 0, cr*cr);
+ ds->hl = snewn(cr*cr, unsigned char);
+ memset(ds->hl, 0, cr*cr);
+
+ return ds;
+}
+
+static void game_free_drawstate(game_drawstate *ds)
+{
+ sfree(ds->hl);
+ sfree(ds->grid);
+ sfree(ds);
+}
+
+static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
+ int x, int y, int hl)
+{
+ int c = state->c, r = state->r, cr = c*r;
+ int tx, ty;
+ int cx, cy, cw, ch;
+ char str[2];
+
+ if (ds->grid[y*cr+x] == state->grid[y*cr+x] && ds->hl[y*cr+x] == hl)
+ return; /* no change required */
+
+ tx = BORDER + x * TILE_SIZE + 2;
+ ty = BORDER + y * TILE_SIZE + 2;
+
+ cx = tx;
+ cy = ty;
+ cw = TILE_SIZE-3;
+ ch = TILE_SIZE-3;
+
+ if (x % r)
+ cx--, cw++;
+ if ((x+1) % r)
+ cw++;
+ if (y % c)
+ cy--, ch++;
+ if ((y+1) % c)
+ ch++;
+
+ clip(fe, cx, cy, cw, ch);
+
+ /* background needs erasing? */
+ if (ds->grid[y*cr+x] || ds->hl[y*cr+x] != hl)
+ draw_rect(fe, cx, cy, cw, ch, hl ? COL_HIGHLIGHT : COL_BACKGROUND);
+
+ /* new number needs drawing? */
+ if (state->grid[y*cr+x]) {
+ str[1] = '\0';
+ str[0] = state->grid[y*cr+x] + '0';
+ if (str[0] > '9')
+ str[0] += 'a' - ('9'+1);
+ draw_text(fe, tx + TILE_SIZE/2, ty + TILE_SIZE/2,
+ FONT_VARIABLE, TILE_SIZE/2, ALIGN_VCENTRE | ALIGN_HCENTRE,
+ state->immutable[y*cr+x] ? COL_CLUE : COL_USER, str);
+ }
+
+ unclip(fe);
+
+ draw_update(fe, cx, cy, cw, ch);
+
+ ds->grid[y*cr+x] = state->grid[y*cr+x];
+ ds->hl[y*cr+x] = hl;
+}
+
+static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
+ game_state *state, int dir, game_ui *ui,
+ float animtime, float flashtime)
+{
+ int c = state->c, r = state->r, cr = c*r;
+ int x, y;
+
+ if (!ds->started) {
+ /*
+ * The initial contents of the window are not guaranteed
+ * and can vary with front ends. To be on the safe side,
+ * all games should start by drawing a big
+ * background-colour rectangle covering the whole window.
+ */
+ draw_rect(fe, 0, 0, XSIZE(cr), YSIZE(cr), COL_BACKGROUND);
+
+ /*
+ * Draw the grid.
+ */
+ for (x = 0; x <= cr; x++) {
+ int thick = (x % r ? 0 : 1);
+ draw_rect(fe, BORDER + x*TILE_SIZE - thick, BORDER-1,
+ 1+2*thick, cr*TILE_SIZE+3, COL_GRID);
+ }
+ for (y = 0; y <= cr; y++) {
+ int thick = (y % c ? 0 : 1);
+ draw_rect(fe, BORDER-1, BORDER + y*TILE_SIZE - thick,
+ cr*TILE_SIZE+3, 1+2*thick, COL_GRID);
+ }
+ }
+
+ /*
+ * Draw any numbers which need redrawing.
+ */
+ for (x = 0; x < cr; x++) {
+ for (y = 0; y < cr; y++) {
+ draw_number(fe, ds, state, x, y,
+ (x == ui->hx && y == ui->hy) ||
+ (flashtime > 0 &&
+ (flashtime <= FLASH_TIME/3 ||
+ flashtime >= FLASH_TIME*2/3)));
+ }
+ }
+
+ /*
+ * Update the _entire_ grid if necessary.
+ */
+ if (!ds->started) {
+ draw_update(fe, 0, 0, XSIZE(cr), YSIZE(cr));
+ ds->started = TRUE;
+ }
+}
+
+static float game_anim_length(game_state *oldstate, game_state *newstate,
+ int dir)
+{
+ return 0.0F;
+}
+
+static float game_flash_length(game_state *oldstate, game_state *newstate,
+ int dir)
+{
+ if (!oldstate->completed && newstate->completed)
+ return FLASH_TIME;
+ return 0.0F;
+}
+
+static int game_wants_statusbar(void)
+{
+ return FALSE;
+}
+
+#ifdef COMBINED
+#define thegame solo
+#endif
+
+const struct game thegame = {
+ "Solo", "games.solo", TRUE,
+ default_params,
+ game_fetch_preset,
+ decode_params,
+ encode_params,
+ free_params,
+ dup_params,
+ game_configure,
+ custom_params,
+ validate_params,
+ new_game_seed,
+ validate_seed,
+ new_game,
+ dup_game,
+ free_game,
+ new_ui,
+ free_ui,
+ make_move,
+ game_size,
+ game_colours,
+ game_new_drawstate,
+ game_free_drawstate,
+ game_redraw,
+ game_anim_length,
+ game_flash_length,
+ game_wants_statusbar,
+};
~mdw / sgt / puzzles / commitdiff