poj 1321

链接：http://poj.org/problem?id=1321

DFS问题.

AC code

#include<iostream>
#include <cstring>
#include <string>
using namespace std;
int n,k,Maze[9][9],sum,visited[9]; //列标记数组
void DFS(int row,int s)
{
	if(s==k) { sum++;return;}
	if(row==n) return;
	for(int i=0;i<n;++i)
	{
		if(Maze[row][i]&&!visited[i])
		{
			visited[i]=true;
			DFS(row+1,s+1);
			visited[i]=false;
		}
	}
	DFS(row+1,s);
}
int main()
{
	while (cin>>n>>k)
	{
		if(n==-1&&k==-1) break;
		int i,j;
		char temp;
		memset(visited,0,sizeof(visited));
		memset(Maze,0,sizeof(Maze));
		for(i=0;i<n;++i)
		{
			for(j=0;j<n;++j)
           { 
			 cin>>temp;
			if(temp=='#') Maze[i][j]=1;
			}
		}
		sum=0;
		DFS(0,0);
		cout<<sum<<endl;
	}
}