http://poj.org/problem?id=1321

#include<stdio.h>
#include<iostream>
#include<math.h>
#include<stdlib.h>
#include<ctype.h>
#include<algorithm>
#include<vector>
#include<string.h>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include <sstream>
#include <time.h>
#include <utility> 
#include <malloc.h> 

using namespace std;

int n, k, c;
char cc;
bool p[10][10];
bool visx[10];
bool visy[10];

void dfs(int pos,int a)
{
	if (a == k)
	{
		c++;
		return;
	}
	while (pos < n*n)
	{
		int x = pos / n;
		int y = pos % n;
		if (p[x][y] && !visx[x] && !visy[y])
		{
			visx[x] = visy[y] = true;
			dfs(pos+1,a+1);
			visx[x] = visy[y] = false;
		}
		pos++;
	}
	return;
}

int main()
{
	while (scanf("%d%d",&n,&k)!=EOF)
	{
		c = 0;
		if (n == -1 && k == -1)
			return 0;
		getchar();
		memset(p,false,sizeof(p));
		for (int i = 0; i < n; i++)
		{
			for (int j = 0; j < n; j++)
			{
				cc = getchar();
				if (cc == '#')
					p[i][j] = true;
				else
					p[i][j] = false;
			}
			getchar();
		}

		memset(visx,false,sizeof(visx));
		memset(visy, false, sizeof(visy));

		dfs(0, 0);

		printf("%d\n",c);
	}
}

poj-1321棋盘摆放 DFS