70pts bfs

rt

#include<bits/stdc++.h>
using namespace std;
char mp[1002][1002];
int n,fs[1002][1002];
int sx,sy,ex,ey;
int dx[4]={1,-1,0,0},dy[4]={0,0,1,-1};
queue<pair<int,int> > q;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++)
            cin>>mp[i];
    cin>>sx>>sy>>ex>>ey;
    fs[sx][sy]=0,mp[sx][sy]='1';
    q.push({sx,sy});
    while(!q.empty()){
        pair<int,int> k=q.front();q.pop();
        int x=k.first,y=k.second;
        for(int i=0;i<4;i++){
            int nx=x+dx[i],ny=y+dy[i];
            if(nx<1 or ny<1 or nx>n or ny>n or mp[nx][ny]=='1') continue;
            fs[nx][ny]=fs[x][y]+1;
            mp[nx][ny]='1';
            q.push({nx,ny});
        }
    }
    cout<<fs[ex][ey];
    return 0;
}