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Implement speculative value-placement branching

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This commit is contained in:
Gabriel Tofvesson 2020-02-25 18:37:15 +01:00
parent ca8809a5e1
commit 749ad4a260
2 changed files with 64 additions and 13 deletions
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53
board.c
View File

@ -117,7 +117,7 @@ board_unmark (
bool
board_has_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y
)
@ -132,7 +132,7 @@ board_has_value (
element_value
board_get_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y
)
@ -163,7 +163,7 @@ board_is_marked (
bool
board_can_place_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y,
element_value value
@ -574,13 +574,11 @@ board_place (
board_unmark (board, target_x, target_y, value);
}
/* Set value */
/* Set value */
board_set (board, x, y, value);
/* Update board complexity */
board_refresh_complexity (board);
return true;
return board_refresh_complexity (board);
}
else return false;
}
@ -588,7 +586,38 @@ board_place (
}
void
struct board *
board_place_speculative (
const struct board *board,
board_pos x,
board_pos y,
element_value value
)
{
if (is_in_bounds (x, y) && is_valid_value (value))
{
/* Ensure value can be placed*/
if (board_can_place_value (board, x, y, value))
{
/* Create duplicate and place value */
struct board *board_duplicate = malloc (sizeof (struct board));
board_copy (board, board_duplicate);
if (! board_place (board_duplicate, x, y, value))
{
free (board_duplicate);
return NULL;
}
return board_duplicate;
}
else return NULL;
}
else ERROR("Invalid parameters to function board_place_speculative()");
}
bool
board_refresh_complexity (struct board *board)
{
board_update_all_marks (board);
@ -601,17 +630,23 @@ board_refresh_complexity (struct board *board)
struct board_element *elem = BOARD_ELEM (board, x, y);
if (elem->complexity < board->complexity)
{
/* If complexity is somehow 0, we have an invalid board state */
if (elem->complexity == 0)
return false;
board->complexity = elem->complexity;
/* Short-circuit function on comlpexity=1, since it can't go lower */
if (board->complexity == 1)
return;
return true;
}
}
/* If there are no complex board elements, board is solved */
if (board->complexity == 10)
board->complexity = 0;
return true;
}

24
board.h
View File

@ -102,7 +102,7 @@ board_unmark (
*/
bool
board_has_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y
);
@ -115,7 +115,7 @@ board_has_value (
*/
element_value
board_get_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y
);
@ -141,7 +141,7 @@ board_is_marked (
*/
bool
board_can_place_value (
struct board *board,
const struct board *board,
board_pos x,
board_pos y,
element_value value
@ -251,11 +251,27 @@ board_place (
);
/**
* Place a speculative value. This allocates a duplicate board with the element
* placed at the given location, if possible, while leaving the given board
* untouched
*
* NOTE: If element cannot be placed, this returns NULL
*/
struct board *
board_place_speculative (
const struct board *board,
board_pos x,
board_pos y,
element_value value
);
/**
* Recomputes board complexity by searching all elements on board for the
* lowest complexity
*/
void
bool
board_refresh_complexity (struct board *board);