[kuangbin带你飞]专题一 简单搜索 - A - 棋盘问题

#include<iostream>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
using namespace std;
struct node
{
    int x;
    int y;
};
int n, k, l, ans;
bool w[10], h[10];
vector<node>dot;
void bfs(int a, int b)
{
    if(a==k+1)
    {
        ans++;
        return;
    }
    for(int i = b; i < l; i++)
    {
        if(w[dot[i].x] || h[dot[i].y])    continue;
        else
        {
            w[dot[i].x] = h[dot[i].y] = true;
            bfs(a+1, i+1);
            w[dot[i].x] = h[dot[i].y] = false;
        }
    }
    return;
}
int main()
{
//    freopen("in.in","r",stdin);
    string c;
    node tmp;
    while(cin>>n>>k)
    {
        dot.clear();
        memset(w,0,sizeof(w));
        memset(h,0,sizeof(h));
        if(n==-1)    break;
        for(int i = 1; i <= n; i++)
        {
            cin>>c;
            for(int j = 1; j <= n; j++)
            {
                
                if(c[j-1]=='#')
                {
                    tmp.x = i;
                    tmp.y = j;
                    dot.push_back(tmp);
                }
            }            
        }

        l = dot.size();
        ans = 0;
        bfs(1,0);
        cout<<ans<<endl;
    }
    return 0;
}