POJ-棋盘问题（DFS）

#include<iostream>
#include<cstring>
#include<string>
using namespace std;
int visited[9];
int K,N,counts,way;
char map[9][9];
void dfs(int k) {
	if (way == K) {
		counts++;
		return;
	}
	if (k >= N) {
		return;
	}
	for (int i = 0; i < N; i++) {
		if (map[k][i] == '#'&&visited[i]==0) {
			visited[i] = 1;
			way++;
			dfs(k + 1);
			way--;
			visited[i] = 0;
		}
	}
	dfs(k + 1);
}
int main() {
	while (cin >> N >> K) {
		if (N == -1)
			break;
		memset(visited, 0, sizeof(visited));
		memset(map, 0, sizeof(map));
		counts=way = 0;
		for (int i = 0; i < N; i++) {
			for (int j = 0; j < N; j++) {
				cin >> map[i][j];
			}
		}
		dfs(0);
		cout << counts << endl;
	}
}