Created
May 23, 2013 10:13
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Solve sudoku
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#include <iostream> | |
#include <cstdio> | |
#include <vector> | |
#include <utility> | |
using namespace std; | |
int in[9][9] = {{9, 0, 5, 0, 0, 7, 8, 0, 1}, | |
{0, 0, 6, 5, 0, 0, 3, 0, 0}, | |
{0, 3, 0, 6, 0, 9, 0, 0, 0}, | |
{0, 0, 9, 0, 0, 6, 0, 0, 4}, | |
{0, 0, 0, 0, 0, 0, 0, 0, 0}, | |
{8, 0, 0, 1, 0, 0, 7, 0, 0}, | |
{0, 0, 0, 9, 0, 4, 0, 1, 0}, | |
{0, 0, 4, 0, 0, 5, 9, 0, 0}, | |
{6, 0, 2, 7, 0, 0, 5, 0, 8}}; | |
int out[9][9]; | |
int pos[9][9]; | |
bool solve(int d) { | |
//printf("d=%d\n", d); | |
if (81 == d) { | |
return true; | |
} | |
unsigned i = d / 9, j = d % 9; | |
if (in[i][j] > 0) { | |
return solve(d + 1); | |
} | |
for (unsigned k = 1; k <= 9; ++k) { | |
if (!(pos[i][j] & (1 << k))) { | |
//printf("k=%d\n", k); | |
out[i][j] = k; | |
int m = 1 << k; | |
vector<pair<int, int> > v; | |
for (unsigned p = 0; p < 9; ++p) { | |
if (!(pos[i][p] & m)) { | |
pos[i][p] |= m; | |
v.push_back(make_pair(i, p)); | |
} | |
if (!(pos[p][j] & m)) { | |
pos[p][j] |= m; | |
v.push_back(make_pair(p, j)); | |
} | |
} | |
unsigned si = i / 3 * 3, sj = j / 3 * 3; | |
for (unsigned p = 0; p < 3; ++p) { | |
for (unsigned q = 0; q < 3; ++q) { | |
if (!(pos[si + p][sj + q])) { | |
pos[si + p][sj + q] |= m; | |
v.push_back(make_pair(si + p, sj + q)); | |
} | |
} | |
} | |
if (solve(d + 1)) { | |
return true; | |
} | |
//printf("-------\n"); | |
for (unsigned p = 0; p < v.size(); ++p) { | |
pos[v[p].first][v[p].second] &= ~m; | |
} | |
} | |
} | |
return false; | |
} | |
int main() { | |
for (unsigned i = 0; i < 9; ++i) { | |
for (unsigned j = 0; j < 9; ++j) { | |
printf("%d, ", in[i][j]); | |
if (in[i][j] > 0) { | |
out[i][j] = in[i][j]; | |
int m = 1 << in[i][j]; | |
for (unsigned k = 0; k < 9; ++k) { | |
pos[i][k] |= m; | |
pos[k][j] |= m; | |
} | |
unsigned si = i/3 * 3, sj = j/3 * 3; | |
for (unsigned k = 0; k < 3; ++k) { | |
for (unsigned p = 0; p < 3; ++p) { | |
pos[si + k][sj + p] |= m; | |
} | |
} | |
} | |
} | |
printf("\n"); | |
} | |
printf("-----------------\n"); | |
if (solve(0)) { | |
for (unsigned i = 0; i < 9; ++i) { | |
for (unsigned j = 0; j < 9; ++j) { | |
printf("%d, ", out[i][j]); | |
} | |
printf("\n"); | |
} | |
} | |
else { | |
printf("No solution."); | |
} | |
return 0; | |
} |
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