New {en,de}code_ui functions should be static. Oops.
[sgt/puzzles] / flip.c
diff --git a/flip.c b/flip.c
index fd31647..4f78ec7 100644 (file)
--- a/flip.c
+++ b/flip.c
@@ -3,15 +3,6 @@
  * where each click toggles an overlapping set of lights.
  */
 
-/*
- * TODO:
- * 
- *  - `Solve' could mark the squares you must click to solve
- *     + infrastructure change: this would mean the Solve operation
- *      must receive the current game_state as well as the initial
- *      one, which I've been wondering about for a while
- */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -28,6 +19,7 @@ enum {
     COL_RIGHT,
     COL_GRID,
     COL_DIAG,
+    COL_HINT,
     NCOLOURS
 };
 
@@ -37,6 +29,7 @@ enum {
 #define COORD(x)  ( (x) * TILE_SIZE + BORDER )
 #define FROMCOORD(x)  ( ((x) - BORDER + TILE_SIZE) / TILE_SIZE - 1 )
 
+#define ANIM_TIME 0.25F
 #define FLASH_FRAME 0.07F
 
 /*
@@ -64,7 +57,7 @@ struct matrix {
 
 struct game_state {
     int w, h;
-    int moves, completed;
+    int moves, completed, cheated, hints_active;
     unsigned char *grid;               /* array of w*h */
     struct matrix *matrix;
 };
@@ -354,7 +347,7 @@ static void addneighbours(tree234 *t, int w, int h, int cx, int cy,
 }
 
 static char *new_game_desc(game_params *params, random_state *rs,
-                          game_aux_info **aux, int interactive)
+                          char **aux, int interactive)
 {
     int w = params->w, h = params->h, wh = w * h;
     int i, j;
@@ -597,14 +590,11 @@ static char *new_game_desc(game_params *params, random_state *rs,
     sprintf(ret, "%s,%s", mbmp, gbmp);
     sfree(mbmp);
     sfree(gbmp);
+    sfree(matrix);
+    sfree(grid);
     return ret;
 }
 
-static void game_free_aux_info(game_aux_info *aux)
-{
-    assert(!"Shouldn't happen");
-}
-
 static char *validate_desc(game_params *params, char *desc)
 {
     int w = params->w, h = params->h, wh = w * h;
@@ -632,6 +622,8 @@ static game_state *new_game(midend_data *me, game_params *params, char *desc)
     state->w = w;
     state->h = h;
     state->completed = FALSE;
+    state->cheated = FALSE;
+    state->hints_active = FALSE;
     state->moves = 0;
     state->matrix = snew(struct matrix);
     state->matrix->refcount = 1;
@@ -650,6 +642,8 @@ static game_state *dup_game(game_state *state)
     ret->w = state->w;
     ret->h = state->h;
     ret->completed = state->completed;
+    ret->cheated = state->cheated;
+    ret->hints_active = state->hints_active;
     ret->moves = state->moves;
     ret->matrix = state->matrix;
     state->matrix->refcount++;
@@ -669,10 +663,193 @@ static void free_game(game_state *state)
     sfree(state);
 }
 
-static game_state *solve_game(game_state *state, game_aux_info *aux,
-                             char **error)
+static void rowxor(unsigned char *row1, unsigned char *row2, int len)
 {
-    return NULL;
+    int i;
+    for (i = 0; i < len; i++)
+       row1[i] ^= row2[i];
+}
+
+static char *solve_game(game_state *state, game_state *currstate,
+                       char *aux, char **error)
+{
+    int w = state->w, h = state->h, wh = w * h;
+    unsigned char *equations, *solution, *shortest;
+    int *und, nund;
+    int rowsdone, colsdone;
+    int i, j, k, len, bestlen;
+    char *ret;
+
+    /*
+     * Set up a list of simultaneous equations. Each one is of
+     * length (wh+1) and has wh coefficients followed by a value.
+     */
+    equations = snewn((wh + 1) * wh, unsigned char);
+    for (i = 0; i < wh; i++) {
+       for (j = 0; j < wh; j++)
+           equations[i * (wh+1) + j] = currstate->matrix->matrix[j*wh+i];
+       equations[i * (wh+1) + wh] = currstate->grid[i] & 1;
+    }
+
+    /*
+     * Perform Gaussian elimination over GF(2).
+     */
+    rowsdone = colsdone = 0;
+    nund = 0;
+    und = snewn(wh, int);
+    do {
+       /*
+        * Find the leftmost column which has a 1 in it somewhere
+        * outside the first `rowsdone' rows.
+        */
+       j = -1;
+       for (i = colsdone; i < wh; i++) {
+           for (j = rowsdone; j < wh; j++)
+               if (equations[j * (wh+1) + i])
+                   break;
+           if (j < wh)
+               break;                 /* found one */
+           /*
+            * This is a column which will not have an equation
+            * controlling it. Mark it as undetermined.
+            */
+           und[nund++] = i;
+       }
+
+       /*
+        * If there wasn't one, then we've finished: all remaining
+        * equations are of the form 0 = constant. Check to see if
+        * any of them wants 0 to be equal to 1; this is the
+        * condition which indicates an insoluble problem
+        * (therefore _hopefully_ one typed in by a user!).
+        */
+       if (i == wh) {
+           for (j = rowsdone; j < wh; j++)
+               if (equations[j * (wh+1) + wh]) {
+                   *error = "No solution exists for this position";
+                   sfree(equations);
+                   sfree(und);
+                   return NULL;
+               }
+           break;
+       }
+
+       /*
+        * We've found a 1. It's in column i, and the topmost 1 in
+        * that column is in row j. Do a row-XOR to move it up to
+        * the topmost row if it isn't already there.
+        */
+       assert(j != -1);
+       if (j > rowsdone)
+           rowxor(equations + rowsdone*(wh+1), equations + j*(wh+1), wh+1);
+
+       /*
+        * Do row-XORs to eliminate that 1 from all rows below the
+        * topmost row.
+        */
+       for (j = rowsdone + 1; j < wh; j++)
+           if (equations[j*(wh+1) + i])
+               rowxor(equations + j*(wh+1),
+                      equations + rowsdone*(wh+1), wh+1);
+
+       /*
+        * Mark this row and column as done.
+        */
+       rowsdone++;
+       colsdone = i+1;
+
+       /*
+        * If we've done all the rows, terminate.
+        */
+    } while (rowsdone < wh);
+
+    /*
+     * If we reach here, we have the ability to produce a solution.
+     * So we go through _all_ possible solutions (each
+     * corresponding to a set of arbitrary choices of those
+     * components not directly determined by an equation), and pick
+     * one requiring the smallest number of flips.
+     */
+    solution = snewn(wh, unsigned char);
+    shortest = snewn(wh, unsigned char);
+    memset(solution, 0, wh);
+    bestlen = wh + 1;
+    while (1) {
+       /*
+        * Find a solution based on the current values of the
+        * undetermined variables.
+        */
+       for (j = rowsdone; j-- ;) {
+           int v;
+
+           /*
+            * Find the leftmost set bit in this equation.
+            */
+           for (i = 0; i < wh; i++)
+               if (equations[j * (wh+1) + i])
+                   break;
+           assert(i < wh);                    /* there must have been one! */
+
+           /*
+            * Compute this variable using the rest.
+            */
+           v = equations[j * (wh+1) + wh];
+           for (k = i+1; k < wh; k++)
+               if (equations[j * (wh+1) + k])
+                   v ^= solution[k];
+
+           solution[i] = v;
+       }
+
+       /*
+        * Compare this solution to the current best one, and
+        * replace the best one if this one is shorter.
+        */
+       len = 0;
+       for (i = 0; i < wh; i++)
+           if (solution[i])
+               len++;
+       if (len < bestlen) {
+           bestlen = len;
+           memcpy(shortest, solution, wh);
+       }
+
+       /*
+        * Now increment the binary number given by the
+        * undetermined variables: turn all 1s into 0s until we see
+        * a 0, at which point we turn it into a 1.
+        */
+       for (i = 0; i < nund; i++) {
+           solution[und[i]] = !solution[und[i]];
+           if (solution[und[i]])
+               break;
+       }
+
+       /*
+        * If we didn't find a 0 at any point, we have wrapped
+        * round and are back at the start, i.e. we have enumerated
+        * all solutions.
+        */
+       if (i == nund)
+           break;
+    }
+
+    /*
+     * We have a solution. Produce a move string encoding the
+     * solution.
+     */
+    ret = snewn(wh + 2, char);
+    ret[0] = 'S';
+    for (i = 0; i < wh; i++)
+       ret[i+1] = shortest[i] ? '1' : '0';
+    ret[wh+1] = '\0';
+
+    sfree(shortest);
+    sfree(solution);
+    sfree(equations);
+    sfree(und);
+
+    return ret;
 }
 
 static char *game_text_format(game_state *state)
@@ -689,6 +866,15 @@ static void free_ui(game_ui *ui)
 {
 }
 
+static char *encode_ui(game_ui *ui)
+{
+    return NULL;
+}
+
+static void decode_ui(game_ui *ui, char *encoding)
+{
+}
+
 static void game_changed_state(game_ui *ui, game_state *oldstate,
                                game_state *newstate)
 {
@@ -700,38 +886,68 @@ struct game_drawstate {
     int tilesize;
 };
 
-static game_state *make_move(game_state *from, game_ui *ui, game_drawstate *ds,
-                             int x, int y, int button)
+static char *interpret_move(game_state *state, game_ui *ui, game_drawstate *ds,
+                           int x, int y, int button)
 {
-    int w = from->w, h = from->h, wh = w * h;
-    game_state *ret;
+    int w = state->w, h = state->h /*, wh = w * h */;
+    char buf[80];
 
     if (button == LEFT_BUTTON) {
         int tx = FROMCOORD(x), ty = FROMCOORD(y);
         if (tx >= 0 && tx < w && ty >= 0 && ty < h) {
-            int i, j, done;
+           sprintf(buf, "M%d,%d", tx, ty);
+           return dupstr(buf);
+        }
+    }
 
-            ret = dup_game(from);
+    return NULL;
+}
 
-           if (!ret->completed)
-               ret->moves++;
+static game_state *execute_move(game_state *from, char *move)
+{
+    int w = from->w, h = from->h, wh = w * h;
+    game_state *ret;
+    int x, y;
+
+    if (move[0] == 'S' && strlen(move) == wh+1) {
+       int i;
+
+       ret = dup_game(from);
+       ret->hints_active = TRUE;
+       ret->cheated = TRUE;
+       for (i = 0; i < wh; i++) {
+           ret->grid[i] &= ~2;
+           if (move[i+1] != '0')
+               ret->grid[i] |= 2;
+       }
+       return ret;
+    } else if (move[0] == 'M' &&
+              sscanf(move+1, "%d,%d", &x, &y) == 2 &&
+       x >= 0 && x < w && y >= 0 && y < h) {
+       int i, j, done;
 
-            i = ty * w + tx;
+       ret = dup_game(from);
 
-           done = TRUE;
-            for (j = 0; j < wh; j++) {
-                ret->grid[j] ^= ret->matrix->matrix[i*wh+j];
-               if (ret->grid[j] & 1)
-                   done = FALSE;
-           }
-           if (done)
-               ret->completed = TRUE;
+       if (!ret->completed)
+           ret->moves++;
 
-            return ret;
-        }
-    }
+       i = y * w + x;
 
-    return NULL;
+       done = TRUE;
+       for (j = 0; j < wh; j++) {
+           ret->grid[j] ^= ret->matrix->matrix[i*wh+j];
+           if (ret->grid[j] & 1)
+               done = FALSE;
+       }
+       ret->grid[i] ^= 2;             /* toggle hint */
+       if (done) {
+           ret->completed = TRUE;
+           ret->hints_active = FALSE;
+       }
+
+       return ret;
+    } else
+       return NULL;                   /* can't parse move string */
 }
 
 /* ----------------------------------------------------------------------
@@ -781,6 +997,10 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_DIAG * 3 + 1] = ret[COL_GRID * 3 + 1];
     ret[COL_DIAG * 3 + 2] = ret[COL_GRID * 3 + 2];
 
+    ret[COL_HINT * 3 + 0] = 1.0F;
+    ret[COL_HINT * 3 + 1] = 0.0F;
+    ret[COL_HINT * 3 + 2] = 0.0F;
+
     *ncolours = NCOLOURS;
     return ret;
 }
@@ -808,7 +1028,8 @@ static void game_free_drawstate(game_drawstate *ds)
 }
 
 static void draw_tile(frontend *fe, game_drawstate *ds,
-                     game_state *state, int x, int y, int tile)
+                     game_state *state, int x, int y, int tile, int anim,
+                     float animtime)
 {
     int w = ds->w, h = ds->h, wh = w * h;
     int bx = x * TILE_SIZE + BORDER, by = y * TILE_SIZE + BORDER;
@@ -817,7 +1038,30 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
     clip(fe, bx+1, by+1, TILE_SIZE-1, TILE_SIZE-1);
 
     draw_rect(fe, bx+1, by+1, TILE_SIZE-1, TILE_SIZE-1,
-              tile == 1 ? COL_WRONG : COL_RIGHT);
+              anim ? COL_BACKGROUND : tile & 1 ? COL_WRONG : COL_RIGHT);
+    if (anim) {
+       /*
+        * Draw a polygon indicating that the square is diagonally
+        * flipping over.
+        */
+       int coords[8], colour;
+
+       coords[0] = bx + TILE_SIZE;
+       coords[1] = by;
+       coords[2] = bx + TILE_SIZE * animtime;
+       coords[3] = by + TILE_SIZE * animtime;
+       coords[4] = bx;
+       coords[5] = by + TILE_SIZE;
+       coords[6] = bx + TILE_SIZE - TILE_SIZE * animtime;
+       coords[7] = by + TILE_SIZE - TILE_SIZE * animtime;
+
+       colour = (tile & 1 ? COL_WRONG : COL_RIGHT);
+       if (animtime < 0.5)
+           colour = COL_WRONG + COL_RIGHT - colour;
+
+       draw_polygon(fe, coords, 4, TRUE, colour);
+       draw_polygon(fe, coords, 4, FALSE, COL_GRID);
+    }
 
     /*
      * Draw a little diagram in the tile which indicates which
@@ -840,6 +1084,22 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
                 }
            }
 
+    /*
+     * Draw a hint rectangle if required.
+     */
+    if (tile & 2) {
+       int x1 = bx + TILE_SIZE / 20, x2 = bx + TILE_SIZE - TILE_SIZE / 20;
+       int y1 = by + TILE_SIZE / 20, y2 = by + TILE_SIZE - TILE_SIZE / 20;
+       int i = 3;
+       while (i--) {
+           draw_line(fe, x1, y1, x2, y1, COL_HINT);
+           draw_line(fe, x1, y2, x2, y2, COL_HINT);
+           draw_line(fe, x1, y1, x1, y2, COL_HINT);
+           draw_line(fe, x2, y1, x2, y2, COL_HINT);
+           x1++, y1++, x2--, y2--;
+       }
+    }
+
     unclip(fe);
 
     draw_update(fe, bx+1, by+1, TILE_SIZE-1, TILE_SIZE-1);
@@ -879,10 +1139,13 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
     else
        flashframe = -1;
 
+    animtime /= ANIM_TIME;            /* scale it so it goes from 0 to 1 */
+
     for (i = 0; i < wh; i++) {
         int x = i % w, y = i / w;
        int fx, fy, fd;
        int v = state->grid[i];
+       int vv;
 
        if (flashframe >= 0) {
            fx = (w+1)/2 - min(x+1, w-x);
@@ -893,17 +1156,28 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
            else if (fd == flashframe - 1)
                v &= ~1;
        }
-       
-        if (ds->tiles[i] != v) {
-            draw_tile(fe, ds, state, x, y, v);
-            ds->tiles[i] = v;
+
+       if (!state->hints_active)
+           v &= ~2;
+
+       if (oldstate && state->grid[i] != oldstate->grid[i])
+           vv = 255;                  /* means `animated' */
+       else
+           vv = v;
+
+        if (ds->tiles[i] == 255 || vv == 255 || ds->tiles[i] != vv) {
+            draw_tile(fe, ds, state, x, y, v, vv == 255, animtime);
+            ds->tiles[i] = vv;
         }
     }
 
     {
        char buf[256];
 
-       sprintf(buf, "%sMoves: %d", state->completed ? "COMPLETED! " : "",
+       sprintf(buf, "%sMoves: %d",
+               (state->completed ? 
+                (state->cheated ? "Auto-solved. " : "COMPLETED! ") :
+                (state->cheated ? "Auto-solver used. " : "")),
                state->moves);
 
        status_bar(fe, buf);
@@ -913,7 +1187,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 static float game_anim_length(game_state *oldstate, game_state *newstate,
                              int dir, game_ui *ui)
 {
-    return 0.0F;
+    return ANIM_TIME;
 }
 
 static float game_flash_length(game_state *oldstate, game_state *newstate,
@@ -940,7 +1214,7 @@ static int game_timing_state(game_state *state)
 #endif
 
 const struct game thegame = {
-    "Flip", NULL,
+    "Flip", "games.flip",
     default_params,
     game_fetch_preset,
     decode_params,
@@ -950,17 +1224,19 @@ const struct game thegame = {
     TRUE, game_configure, custom_params,
     validate_params,
     new_game_desc,
-    game_free_aux_info,
     validate_desc,
     new_game,
     dup_game,
     free_game,
-    FALSE, solve_game,
+    TRUE, solve_game,
     FALSE, game_text_format,
     new_ui,
     free_ui,
+    encode_ui,
+    decode_ui,
     game_changed_state,
-    make_move,
+    interpret_move,
+    execute_move,
     game_size,
     game_colours,
     game_new_drawstate,