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Prevent starting in a solved state in Fifteen & Flood

Browse Source 
(cherry picked from Android port, commit
cb38abdc71780bd9b393b90514396c338306fa69)
This commit is contained in:
Chris Boyle
2016-12-21 20:01:25 +00:00
committed by Ben Harris
parent 0d43753ff2
commit f967bfa87b
2 changed files with 78 additions and 69 deletions
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141
fifteen.c
View File

@ -156,6 +156,14 @@ static int perm_parity(int *perm, int n)
return ret;
}
static int is_completed(int *tiles, int n) {
int p;
for (p = 0; p < n; p++)
if (tiles[p] != (p < n-1 ? p+1 : 0))
return 0;
return 1;
}
static char *new_game_desc(const game_params *params, random_state *rs,
char **aux, bool interactive)
{
@ -171,81 +179,83 @@ static char *new_game_desc(const game_params *params, random_state *rs,
tiles = snewn(n, int);
used = snewn(n, bool);
for (i = 0; i < n; i++) {
tiles[i] = -1;
used[i] = false;
}
do {
for (i = 0; i < n; i++) {
tiles[i] = -1;
used[i] = false;
}
gap = random_upto(rs, n);
tiles[gap] = 0;
used[0] = true;
gap = random_upto(rs, n);
tiles[gap] = 0;
used[0] = true;
/*
* Place everything else except the last two tiles.
*/
for (x = 0, i = n-1; i > 2; i--) {
int k = random_upto(rs, i);
int j;
/*
* Place everything else except the last two tiles.
*/
for (x = 0, i = n - 1; i > 2; i--) {
int k = random_upto(rs, i);
int j;
for (j = 0; j < n; j++)
if (!used[j] && (k-- == 0))
break;
for (j = 0; j < n; j++)
if (!used[j] && (k-- == 0))
break;
assert(j < n && !used[j]);
used[j] = true;
assert(j < n && !used[j]);
used[j] = true;
while (tiles[x] >= 0)
x++;
assert(x < n);
tiles[x] = j;
}
/*
* Find the last two locations, and the last two pieces.
*/
while (tiles[x] >= 0)
x++;
assert(x < n);
tiles[x] = j;
}
/*
* Find the last two locations, and the last two pieces.
*/
while (tiles[x] >= 0)
x1 = x;
x++;
assert(x < n);
x1 = x;
x++;
while (tiles[x] >= 0)
x++;
assert(x < n);
x2 = x;
while (tiles[x] >= 0)
x++;
assert(x < n);
x2 = x;
for (i = 0; i < n; i++)
if (!used[i])
break;
p1 = i;
for (i = p1+1; i < n; i++)
if (!used[i])
break;
p2 = i;
for (i = 0; i < n; i++)
if (!used[i])
break;
p1 = i;
for (i = p1 + 1; i < n; i++)
if (!used[i])
break;
p2 = i;
/*
* Determine the required parity of the overall permutation.
* This is the XOR of:
*
* - The chessboard parity ((x^y)&1) of the gap square. The
* bottom right counts as even.
*
* - The parity of n. (The target permutation is 1,...,n-1,0
* rather than 0,...,n-1; this is a cyclic permutation of
* the starting point and hence is odd iff n is even.)
*/
parity = PARITY_P(params, gap);
/*
* Determine the required parity of the overall permutation.
* This is the XOR of:
*
* - The chessboard parity ((x^y)&1) of the gap square. The
* bottom right counts as even.
*
* - The parity of n. (The target permutation is 1,...,n-1,0
* rather than 0,...,n-1; this is a cyclic permutation of
* the starting point and hence is odd iff n is even.)
*/
parity = PARITY_P(params, gap);
/*
* Try the last two tiles one way round. If that fails, swap
* them.
*/
tiles[x1] = p1;
tiles[x2] = p2;
if (perm_parity(tiles, n) != parity) {
tiles[x1] = p2;
tiles[x2] = p1;
assert(perm_parity(tiles, n) == parity);
}
/*
* Try the last two tiles one way round. If that fails, swap
* them.
*/
tiles[x1] = p1;
tiles[x2] = p2;
if (perm_parity(tiles, n) != parity) {
tiles[x1] = p2;
tiles[x2] = p1;
assert(perm_parity(tiles, n) == parity);
}
} while (is_completed(tiles, n));
/*
* Now construct the game description, by describing the tile
@ -786,11 +796,8 @@ static game_state *execute_move(const game_state *from, const char *move)
/*
* See if the game has been completed.
*/
if (!ret->completed) {
if (!ret->completed && is_completed(ret->tiles, ret->n)) {
ret->completed = ret->movecount;
for (p = 0; p < ret->n; p++)
if (ret->tiles[p] != (p < ret->n-1 ? p+1 : 0))
ret->completed = 0;
}
return ret;

6
flood.c
View File

@ -552,8 +552,10 @@ static char *new_game_desc(const game_params *params, random_state *rs,
/*
* Invent a random grid.
*/
for (i = 0; i < wh; i++)
scratch->grid[i] = random_upto(rs, params->colours);
do {
for (i = 0; i < wh; i++)
scratch->grid[i] = random_upto(rs, params->colours);
} while (completed(w, h, scratch->grid));
/*
* Run the solver, and count how many moves it uses.