筆記3
#include<bits/stdc++.h>
using namespace std;
int n,ha,la,hb,lb,a[100][100],sum=1;
int dx[5]={0,0,1,0,-1};
int dy[5]={0,1,0,-1,0};
bool check(int x,int y){
????return x>0&&x<=n&&y>0&&y<=n;
}
void dfs(int x,int y){
???? if(x==hb&&y==lb){
???????? cout<<"YES";
???????? exit(0);
???? }
???? for(int i=1;i<=4;i++){
???????? int tx=x+dx[i];
???????? int ty=y+dy[i];
???????? if(a[tx][ty]==0&&check(tx,ty)){
???????????? a[x][y]=1;
???????????? sum++;
???????????? a[tx][ty]=sum;
???????????? dfs(tx,ty);
???????? }
???? }
}
int main(){
???? cin>>n;
???? for(int i=1;i<=n;i++){
???????? for(int k=1;k<=n;k++){
???????? ???? cin>>a[i][k];
???????? }
???? }
???? cin>>ha>>la>>hb>>lb;
???? if(a[ha][la]==1||a[hb][lb]==1){
???????? cout<<"NO";
???????? return 0;
???? }
???? a[ha][la]=1;
???? dfs(ha,la);
???? cout<<"NO";
return 0;
}