poj1321 棋盘问题

#pragma warning(disable:4996)
#include<iostream>
#include<string>
#include<cmath>
#include<ctype.h>
#include<memory.h>
#include<string.h>
#include<algorithm>
#include<map>
#include<iomanip>
#include<set>
#include<list>
#include<vector>
#include<stack>
#include<queue>
#define ll long long int
using namespace std;
const int INF = -1;
int n, k;
int ans = 0;
char a[10][10];
bool vis[10];void dfs(int x,int y)//x 当前行  y 放好了的棋子数量
{if (y == k){ans++;return;}for (int i = x; i <= n; i++){for (int j = 1; j <= n; j++){if (!vis[j] && a[i][j] == '#'){vis[j] = true;dfs(i + 1, y + 1);vis[j] = false;}}}}
int main()
{while (1){memset(vis, 0, sizeof(vis));memset(a, 0, sizeof(a));cin >> n >> k;if (n == -1 && k == -1)break;for (int i = 1; i <= n; i++)for (int j = 1; j <= n; j++)cin >> a[i][j];ans = 0;dfs(1, 0);cout << ans << endl;}return 0;
}