hdu 1760 A New Tetris Game

http://acm.hdu.edu.cn/showproblem.php?pid=1760

dfs + 博弈

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<vector>
#include<queue>
#include<map>
#include<stack>
#include<algorithm>
#include<cmath>

using namespace std;
//#pragma comment(linker,"/STACK:1000000000,1000000000")

#define LL long long

const int N=55;
char a[N][N];
int n,m;
int dfs()
{/*
    for(int i=0;i<n;++i)
    {
        for(int j=0;j<m;++j)
        cout<<a[i][j]<<" ";
        cout<<endl;
    }*/
    int k=0;
    for(int i=1;i<n;++i)
    {
        for(int j=0;j<m-1;++j)
        {
            if(a[i][j]=='1'||a[i-1][j]=='1'||a[i][j+1]=='1'||a[i-1][j+1]=='1')
            continue;
            a[i][j]='1';a[i-1][j]='1';a[i][j+1]='1';a[i-1][j+1]='1';
            if(dfs()==0)
            k=1;
            a[i][j]='0';a[i-1][j]='0';a[i][j+1]='0';a[i-1][j+1]='0';
            if(k)
            break;
        }
        if(k)
        break;
    }
    return k;
}
int main()
{
    //freopen("data.txt","r",stdin);
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        getchar();
        for(int i=0;i<n;++i)
        {
            gets(a[i]);
        }
        if(dfs())
        printf("Yes\n");
        else
        printf("No\n");
    }
    return 0;
}