mirror of
git://git.tartarus.org/simon/puzzles.git
synced 2025-04-21 08:01:30 -07:00
Ahem; forgot about recursion. Recursive solving now shows its
working as well. [originally from svn r6245]
This commit is contained in:
Simon Tatham
146
map.c
146
map.c
@ -804,14 +804,17 @@ static void fourcolour(int *graph, int n, int ngraph, int *colouring,
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struct solver_scratch {
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unsigned char *possible; /* bitmap of colours for each region */
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int *graph;
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int n;
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int ngraph;
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int *bfsqueue;
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int *bfscolour;
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#ifdef SOLVER_DIAGNOSTICS
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int *bfsprev;
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#endif
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int n;
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int ngraph;
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int depth;
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};
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@ -870,15 +873,22 @@ static int place_colour(struct solver_scratch *sc,
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int *graph = sc->graph, n = sc->n, ngraph = sc->ngraph;
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int j, k;
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if (!(sc->possible[index] & (1 << colour)))
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if (!(sc->possible[index] & (1 << colour))) {
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*scannot place %c in region %d\n", 2*sc->depth, "",
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colnames[colour], index);
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#endif
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return FALSE; /* can't do it */
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}
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sc->possible[index] = 1 << colour;
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colouring[index] = colour;
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%s %c in region %d\n", verb, colnames[colour], index);
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printf("%*s%s %c in region %d\n", 2*sc->depth, "",
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verb, colnames[colour], index);
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#endif
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/*
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@ -889,7 +899,8 @@ static int place_colour(struct solver_scratch *sc,
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k = graph[j] - index*n;
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose && (sc->possible[k] & (1 << colour)))
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printf(" ruling out %c in region %d\n", colnames[colour], k);
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printf("%*s ruling out %c in region %d\n", 2*sc->depth, "",
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colnames[colour], k);
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#endif
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sc->possible[k] &= ~(1 << colour);
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}
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@ -925,24 +936,32 @@ static int map_solver(struct solver_scratch *sc,
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{
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int i;
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/*
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* Initialise scratch space.
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*/
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for (i = 0; i < n; i++)
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sc->possible[i] = (1 << FOUR) - 1;
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if (sc->depth == 0) {
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/*
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* Initialise scratch space.
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*/
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for (i = 0; i < n; i++)
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sc->possible[i] = (1 << FOUR) - 1;
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/*
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* Place clues.
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*/
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for (i = 0; i < n; i++)
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if (colouring[i] >= 0) {
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if (!place_colour(sc, colouring, i, colouring[i]
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/*
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* Place clues.
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*/
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for (i = 0; i < n; i++)
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if (colouring[i] >= 0) {
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if (!place_colour(sc, colouring, i, colouring[i]
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#ifdef SOLVER_DIAGNOSTICS
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, "initial clue:"
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, "initial clue:"
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#endif
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))
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return 0; /* the clues aren't even consistent! */
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}
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)) {
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*sinitial clue set is inconsistent\n",
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2*sc->depth, "");
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#endif
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return 0; /* the clues aren't even consistent! */
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}
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}
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}
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/*
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* Now repeatedly loop until we find nothing further to do.
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@ -960,21 +979,35 @@ static int map_solver(struct solver_scratch *sc,
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for (i = 0; i < n; i++) if (colouring[i] < 0) {
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int p = sc->possible[i];
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if (p == 0)
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if (p == 0) {
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*sregion %d has no possible colours left\n",
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2*sc->depth, "", i);
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#endif
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return 0; /* puzzle is inconsistent */
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}
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if ((p & (p-1)) == 0) { /* p is a power of two */
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int c;
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int c, ret;
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for (c = 0; c < FOUR; c++)
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if (p == (1 << c))
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break;
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assert(c < FOUR);
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if (!place_colour(sc, colouring, i, c
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ret = place_colour(sc, colouring, i, c
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#ifdef SOLVER_DIAGNOSTICS
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, "placing"
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, "placing"
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#endif
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))
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return 0; /* found puzzle to be inconsistent */
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);
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/*
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* place_colour() can only fail if colour c was not
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* even a _possibility_ for region i, and we're
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* pretty sure it was because we checked before
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* calling place_colour(). So we can safely assert
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* here rather than having to return a nice
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* friendly error code.
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*/
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assert(ret);
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done_something = TRUE;
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}
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}
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@ -1041,11 +1074,12 @@ static int map_solver(struct solver_scratch *sc,
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if (verbose) {
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char buf[80];
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if (!started)
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printf("adjacent regions %d,%d share colours %s\n",
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j1, j2, colourset(buf, v));
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printf("%*sadjacent regions %d,%d share colours"
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" %s\n", 2*sc->depth, "", j1, j2,
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colourset(buf, v));
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started = TRUE;
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printf(" ruling out %s in region %d\n",
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colourset(buf, sc->possible[k] & v), k);
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printf("%*s ruling out %s in region %d\n",2*sc->depth,
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"", colourset(buf, sc->possible[k] & v), k);
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}
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#endif
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sc->possible[k] &= ~v;
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@ -1176,13 +1210,15 @@ static int map_solver(struct solver_scratch *sc,
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char buf[80], *sep = "";
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int r;
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printf("forcing chain, colour %s, ",
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printf("%*sforcing chain, colour %s, ",
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2*sc->depth, "",
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colourset(buf, origc));
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for (r = j; r != -1; r = sc->bfsprev[r]) {
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printf("%s%d", sep, r);
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sep = "-";
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}
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printf("\n ruling out %s in region %d\n",
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printf("\n%*s ruling out %s in region"
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" %d\n", 2*sc->depth, "",
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colourset(buf, origc), k);
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}
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#endif
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@ -1206,14 +1242,25 @@ static int map_solver(struct solver_scratch *sc,
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for (i = 0; i < n; i++)
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if (colouring[i] < 0)
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break;
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if (i == n)
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if (i == n) {
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*sone solution found\n", 2*sc->depth, "");
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#endif
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return 1; /* success! */
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}
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/*
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* If recursion is not permissible, we now give up.
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*/
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if (difficulty < DIFF_RECURSE)
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if (difficulty < DIFF_RECURSE) {
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*sunable to proceed further without recursion\n",
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2*sc->depth, "");
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#endif
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return 2; /* unable to complete */
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}
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/*
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* Now we've got to do something recursive. So first hunt for a
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@ -1247,6 +1294,11 @@ static int map_solver(struct solver_scratch *sc,
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assert(best >= 0); /* or we'd be solved already */
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose)
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printf("%*srecursing on region %d\n", 2*sc->depth, "", best);
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#endif
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/*
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* Now iterate over the possible colours for this region.
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*/
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@ -1262,11 +1314,27 @@ static int map_solver(struct solver_scratch *sc,
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if (!(sc->possible[best] & (1 << i)))
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continue;
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memcpy(rsc->possible, sc->possible, n);
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memcpy(subcolouring, origcolouring, n * sizeof(int));
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subcolouring[best] = i;
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place_colour(rsc, subcolouring, best, i
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#ifdef SOLVER_DIAGNOSTICS
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, "trying"
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#endif
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);
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subret = map_solver(rsc, graph, n, ngraph,
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subcolouring, difficulty);
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose) {
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printf("%*sretracting %c in region %d; found %s\n",
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2*sc->depth, "", colnames[i], best,
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subret == 0 ? "no solutions" :
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subret == 1 ? "one solution" : "multiple solutions");
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}
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#endif
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/*
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* If this possibility turned up more than one valid
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* solution, or if it turned up one and we already had
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@ -1296,6 +1364,14 @@ static int map_solver(struct solver_scratch *sc,
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sfree(subcolouring);
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free_scratch(rsc);
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#ifdef SOLVER_DIAGNOSTICS
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if (verbose && sc->depth == 0) {
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printf("%*s%s found\n",
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2*sc->depth, "",
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ret == 0 ? "no solutions" :
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ret == 1 ? "one solution" : "multiple solutions");
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}
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#endif
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return ret;
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}
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}
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