代码实现
cpp
#include <bits/stdc++.h>
using namespace std;
const int N = 10;
int a[N][N];
bool col[N][N], row[N][N], st[3][3][N];
bool dfs(int x, int y)
{
// 出口
if(y == 10)
{
x ++;
y = 1;
}
if(x == 10) return true;
if(a[x][y]) return dfs(x, y+1); // 已经填值了
for(int i = 1; i <= 9; i++)
{
if(row[x][i] || col[y][i] || st[(x-1)/3][(y-1)/3][i]) continue; // 剪枝
// 递归搜索
row[x][i] = col[y][i] = st[(x-1)/3][(y-1)/3][i] = 1;
a[x][y] = i;
if(dfs(x, y+1)) return true; // 已经找到结果
// 回溯
row[x][i] = col[y][i] = st[(x-1)/3][(y-1)/3][i] = 0;
a[x][y] = 0;
}
return false; // 前面有填错了
}
int main()
{
for(int i = 1; i <= 9; i++)
{
for (int j = 1; j <= 9; j++)
{
int x; cin >> x;
a[i][j] = x;
if(x) row[i][x] = col[j][x] = st[(i-1)/3][(j-1)/3][x] = 1; // 标记
}
}
dfs(1,1);
for(int i = 1; i <= 9; i++)
{
for (int j = 1; j <= 9; j++) cout << a[i][j] << " ";
cout << endl;
}
return 0;
}