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Aha, here's a nice easy way to generate really hard puzzles. Added

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the missing fifth difficulty level to Solo: `Unreasonable', in which
even set-based reasoning is insufficient and there's no alternative
but to guess a number and backtrack if it didn't work. (Solutions
are still guaranteed unique, however.) In fact it now seems to take
less time to generate a puzzle of this grade than `Advanced'!

[originally from svn r5756]
This commit is contained in:
Simon Tatham
2005-05-07 12:30:29 +00:00
parent b35bedd60c
commit 944997d2f9
2 changed files with 31 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
solo.c
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@ -144,6 +144,7 @@ static int game_fetch_preset(int i, char **name, game_params **params)
{ "3x3 Basic", { 3, 3, SYMM_ROT2, DIFF_SIMPLE } },
{ "3x3 Intermediate", { 3, 3, SYMM_ROT2, DIFF_INTERSECT } },
{ "3x3 Advanced", { 3, 3, SYMM_ROT2, DIFF_SET } },
{ "3x3 Unreasonable", { 3, 3, SYMM_ROT2, DIFF_RECURSIVE } },
{ "3x4 Basic", { 3, 4, SYMM_ROT2, DIFF_SIMPLE } },
{ "4x4 Basic", { 4, 4, SYMM_ROT2, DIFF_SIMPLE } },
};
@ -193,6 +194,8 @@ static game_params *decode_params(char const *string)
string++, ret->diff = DIFF_INTERSECT;
else if (*string == 'a') /* advanced */
string++, ret->diff = DIFF_SET;
else if (*string == 'u') /* unreasonable */
string++, ret->diff = DIFF_RECURSIVE;
} else
string++; /* eat unknown character */
}
@ -239,7 +242,7 @@ static config_item *game_configure(game_params *params)
ret[3].name = "Difficulty";
ret[3].type = C_CHOICES;
ret[3].sval = ":Trivial:Basic:Intermediate:Advanced";
ret[3].sval = ":Trivial:Basic:Intermediate:Advanced:Unreasonable";
ret[3].ival = params->diff;
ret[4].name = NULL;
@ -1368,7 +1371,7 @@ static char *new_game_seed(game_params *params, random_state *rs,
char *seed;
int coords[16], ncoords;
int xlim, ylim;
int maxdiff;
int maxdiff, recursing;
/*
* Adjust the maximum difficulty level to be consistent with
@ -1416,6 +1419,7 @@ static char *new_game_seed(game_params *params, random_state *rs,
* while preserving solubility.
*/
symmetry_limit(params, &xlim, &ylim, params->symm);
recursing = FALSE;
while (1) {
int x, y, i, j;
@ -1452,6 +1456,8 @@ static char *new_game_seed(game_params *params, random_state *rs,
* nsolve.
*/
for (i = 0; i < nlocs; i++) {
int ret;
x = locs[i].x;
y = locs[i].y;
@ -1460,7 +1466,12 @@ static char *new_game_seed(game_params *params, random_state *rs,
for (j = 0; j < ncoords; j++)
grid2[coords[2*j+1]*cr+coords[2*j]] = 0;
if (nsolve(c, r, grid2) <= maxdiff) {
if (recursing)
ret = (rsolve(c, r, grid2, NULL, 2) == 1);
else
ret = (nsolve(c, r, grid2) <= maxdiff);
if (ret) {
for (j = 0; j < ncoords; j++)
grid[coords[2*j+1]*cr+coords[2*j]] = 0;
break;
@ -1469,15 +1480,22 @@ static char *new_game_seed(game_params *params, random_state *rs,
if (i == nlocs) {
/*
* There was nothing we could remove without destroying
* solvability.
* There was nothing we could remove without
* destroying solvability. If we're trying to
* generate a recursion-only grid and haven't
* switched over to rsolve yet, we now do;
* otherwise we give up.
*/
break;
if (maxdiff == DIFF_RECURSIVE && !recursing) {
recursing = TRUE;
} else {
break;
}
}
}
memcpy(grid2, grid, area);
} while (nsolve(c, r, grid2) != maxdiff);
} while (nsolve(c, r, grid2) < maxdiff);
sfree(grid2);
sfree(locs);