#include <iostream>
#include <cstring>
using namespace std;

const int ROW = 10;
const int COL = 10;

int book[COL];
char chess[ROW][COL];
int step, n;
long long  sum;


void DFS(char chess[][COL], int row,int k) {
	if (row > n)
		return;
	if (k == step) {
		sum++;
		return;
	}
		
	for (int j = 1; j <= 2; j++) {
		if (j == 1)
			DFS(chess, row + 1, k); //每一行都有两种选择，放或不放
		if (j == 2) {
			for (int i = 0; i < n; i++) {
				if (book[i] == 0 && chess[row][i] == '#') {
					book[i] = 1;
					DFS(chess, row + 1, k + 1);
					book[i] = 0;
				}
			}
		}
	}
}


int main() {
	while (cin >> n >> step) {
		sum = 0;
		cin.get();
		if (n == -1 && step == -1)
			break;
		for (int i = 0; i < n; i++)
			cin >> chess[i];
	
			DFS(chess, 0, 0);
		


		cout << sum << endl;
	}
}

• Re:简单 (929) PioPio 2016-12-17 11:58:27