sudoku: backtracking: add exhaustive solver

This commit is contained in:
Bruno BELANYI 2020-12-23 15:56:04 +01:00
parent 7fb10cdb0b
commit 886ca8668b
3 changed files with 47 additions and 0 deletions

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@ -9,6 +9,7 @@ project(
) )
sources = [ sources = [
'src/backtracking.c',
'src/constraints.c', 'src/constraints.c',
'src/main.c', 'src/main.c',
'src/solver/last_remaining.c', 'src/solver/last_remaining.c',

36
src/backtracking.c Normal file
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@ -0,0 +1,36 @@
#include "backtracking.h"
#include <stddef.h>
#include "constraints.h"
#include "sudoku.h"
static bool try_at(struct sudoku *grid, size_t i, size_t j, int n) {
grid->grid[i][j] = n;
return !(line_violation(grid, i, j) || column_violation(grid, i, j)
|| square_violation(grid, i, j));
}
bool solve_backtracking(struct sudoku *grid) {
if (!grid)
return false;
for (size_t i = 0; i < 9; ++i) {
for (size_t j = 0; j < 9; ++j) {
if (grid->grid[i][j] != 0)
continue;
for (int n = 1; n <= 9; ++n) {
if (!try_at(grid, i, j, n))
continue;
if (solve_backtracking(grid))
return true;
}
grid->grid[i][j] = 0;
return false;
}
}
return true;
}

10
src/backtracking.h Normal file
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@ -0,0 +1,10 @@
#ifndef BACKTRACKING_H
#define BACKTRACKING_H
#include <stdbool.h>
struct sudoku;
bool solve_backtracking(struct sudoku *grid);
#endif /* !BACKTRACKING_H */