P)J-1321(棋盘问题)

POJ-1321

题解:

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>using namespace std;const int MAXN = 10;
char board[MAXN][MAXN];
bool visit[MAXN];
int ans;
int n, m, k;void INIT()
{memset(visit, 0, sizeof(visit));for(int i = 0; i < MAXN; ++i)for(int j = 0; j < MAXN; ++j) board[i][j] = '.';
}void dfs(int cur)   //cur 表示当前行 
{if(k == m){ans ++;return ;}if(cur > n) return ;for(int i = 1; i <= n; ++i){if(!visit[i] && board[cur][i] == '#'){visit[i] = 1;k ++;dfs(cur + 1);k --;visit[i] = 0;}}dfs(cur + 1);
}int main()
{while(cin >> n >> m && n != -1 && m != -1){INIT();ans = 0;k = 0;for(int i = 1; i <= n; ++i)for(int j = 1; j <= n; ++j) cin >> board[i][j];dfs(0);printf("%d\n", ans);    } 
}