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Patch from James H to fix the occasional generation of puzzles

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harder than requested.

[originally from svn r7113]
This commit is contained in:
Simon Tatham
2007-01-15 20:07:18 +00:00
parent 7a41702606
commit 472deca37c
3 changed files with 59 additions and 40 deletions
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81
latin.c
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@ -619,46 +619,46 @@ int latin_solver_diff_simple(struct latin_solver *solver)
int latin_solver_diff_set(struct latin_solver *solver,
struct latin_solver_scratch *scratch,
int *extreme)
int extreme)
{
int x, y, n, ret, o = solver->o;
/*
* Row-wise set elimination.
*/
for (y = 0; y < o; y++) {
ret = latin_solver_set(solver, scratch, cubepos(0,y,1), o*o, 1
#ifdef STANDALONE_SOLVER
, "set elimination, row %d", YUNTRANS(y)
#endif
);
if (ret > 0) *extreme = 0;
if (ret != 0) return ret;
}
/*
* Column-wise set elimination.
*/
for (x = 0; x < o; x++) {
ret = latin_solver_set(solver, scratch, cubepos(x,0,1), o, 1
if (!extreme) {
/*
* Row-wise set elimination.
*/
for (y = 0; y < o; y++) {
ret = latin_solver_set(solver, scratch, cubepos(0,y,1), o*o, 1
#ifdef STANDALONE_SOLVER
, "set elimination, column %d", x
, "set elimination, row %d", YUNTRANS(y)
#endif
);
if (ret > 0) *extreme = 0;
if (ret != 0) return ret;
}
/*
* Row-vs-column set elimination on a single number.
*/
for (n = 1; n <= o; n++) {
ret = latin_solver_set(solver, scratch, cubepos(0,0,n), o*o, o
);
if (ret != 0) return ret;
}
/*
* Column-wise set elimination.
*/
for (x = 0; x < o; x++) {
ret = latin_solver_set(solver, scratch, cubepos(x,0,1), o, 1
#ifdef STANDALONE_SOLVER
, "positional set elimination, number %d", n
, "set elimination, column %d", x
#endif
);
if (ret > 0) *extreme = 1;
if (ret != 0) return ret;
);
if (ret != 0) return ret;
}
} else {
/*
* Row-vs-column set elimination on a single number
* (much tricker for a human to do!)
*/
for (n = 1; n <= o; n++) {
ret = latin_solver_set(solver, scratch, cubepos(0,0,n), o*o, o
#ifdef STANDALONE_SOLVER
, "positional set elimination, number %d", n
#endif
);
if (ret != 0) return ret;
}
}
return 0;
}
@ -826,7 +826,7 @@ enum { diff_simple = 1, diff_set, diff_extreme, diff_recursive };
static int latin_solver_sub(struct latin_solver *solver, int maxdiff, void *ctx)
{
struct latin_solver_scratch *scratch = latin_solver_new_scratch(solver);
int ret, diff = diff_simple, extreme;
int ret, diff = diff_simple;
assert(maxdiff <= diff_recursive);
/*
@ -859,18 +859,27 @@ static int latin_solver_sub(struct latin_solver *solver, int maxdiff, void *ctx)
if (maxdiff <= diff_simple)
break;
ret = latin_solver_diff_set(solver, scratch, &extreme);
ret = latin_solver_diff_set(solver, scratch, 0);
if (ret < 0) {
diff = diff_impossible;
goto got_result;
} else if (ret > 0) {
diff = max(diff, extreme ? diff_extreme : diff_set);
diff = max(diff, diff_set);
goto cont;
}
if (maxdiff <= diff_set)
break;
ret = latin_solver_diff_set(solver, scratch, 1);
if (ret < 0) {
diff = diff_impossible;
goto got_result;
} else if (ret > 0) {
diff = max(diff, diff_extreme);
goto cont;
}
/*
* Forcing chains.
*/