hdu 1175 连连看

感觉这题挺水的，dfs 6000ms过

#include<iostream>
#include<cstring>
#define maxn 1000+5
using namespace std;
int n,m;
int mapp[maxn][maxn];
int visit[maxn][maxn];
int dir[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
int sx,sy,ex,ey;
int flag;
void dfs(int x,int y,int dire,int cha)
{
	visit[x][y]=1;
	if(flag){return;}
	if(x==ex&&y==ey) {flag=1;return;}
	for(int i=0;i<4;i++)
	{
		int xx=x+dir[i][0],yy=y+dir[i][1],diree=dire,chaa=cha;
		if(diree!=i) diree=i,chaa++;
		if(xx<0||xx>=n||yy<0||yy>=m||chaa>3||(mapp[xx][yy]&&(xx!=ex||yy!=ey))||visit[xx][yy])
		{
			//cout<<xx<<" "<<yy<<"b"<<endl;
			continue;
		}
		//cout<<xx<<" "<<yy<<" "<<diree<<" "<<chaa<<"a"<<endl;
		dfs(xx,yy,diree,chaa);
		//cout<<xx<<' '<<yy<<endl;
		visit[xx][yy]=0;
	}
}
int main()
{
	while(cin>>n>>m&&n&&m)
	{
		for(int i=0;i<n;i++)
		{
			for(int j=0;j<m;j++)
			{
				cin>>mapp[i][j];
			}
		}
		int p;
		cin>>p;
		while(p--)
		{
			cin>>sx>>sy>>ex>>ey;
			sx--;sy--;ex--;ey--;
			if(!mapp[sx][sy]||!mapp[ex][ey]||mapp[sx][sy]!=mapp[ex][ey]||(sx==ex&&sy==ey)) {cout<<"NO"<<endl;continue;}
			memset(visit,0,sizeof(visit));
			flag=0;
			dfs(sx,sy,-1,0);
			if(flag) cout<<"YES"<<endl;
			else cout<<"NO"<<endl;
		}
	}
	return 0;
}