pku 1321 棋盘问题 简单DFS

#include <iostream>using namespace std;int map[8][8];int visited[8][8];int N, K;int total;bool ok(int n, int j){for(int i = 0; i < n; ++i)if(visited[i][j])return false;return true;}//已遍历行数n, 已取可行行数cntvoid dfs(int n, int cnt){if(cnt == K){total++;return;}if(n >= N)return;//取这一行中某一可行的列for(int i = 0; i < N; ++i)if(!visited[n][i] && map[n][i] && ok(n, i)){visited[n][i] = true;dfs(n+1, cnt+1); //此处取列后,列的统计数cnt加1visited[n][i] = false;}//不取第n行的任意列dfs(n+1, cnt); //此处没有取列,列的统计数cnt不变}int main(){char ch;while(scanf("%d%d", &N, &K) && N != -1){memset(visited, 0, sizeof(visited));memset(map, 0, sizeof(map));for(int i = 0; i < N; ++i)for(int j = 0; j < N; ++j){cin >> ch;if(ch == '#')map[i][j] = 1;}total = 0;dfs(0, 0);printf("%d/n", total);}return 0;}