求调

#include <bits/stdc++.h>
using namespace std;
int n;
int x2,y2; 
int fx[]={0,1,-1,0};
int fy[]={1,0,0,-1};
char a[1003][1003];
struct node{
    int x;
    int y;
    int step;
};
queue<node> q;
bool vis[1003][1003];
void bfs(int x1,int y1)
{
    q.push({1,1,0});
    vis[1][1]=1;
    while(!q.empty()){
        node fir=q.front();
        for(int i=0;i<4;i++)
        {
            int dx=fir.x+fx[i];
            int dy=fir.y+fy[i];
            if(dx==n&&dy==n)
            {
                cout<<fir.step+1;
                exit(0);
            }
            if(dx>=x1&&dx<=n&&dy>=y1&&dy<=n&&a[dx][dy]=='0'&&!vis[dx][dy])
            {
                vis[dx][dy]=1;
                q.push({dx,dy,fir.step+1});
            }
        }
        q.pop();
    }
}
int main()
{
    int x1,y1;
    ios::sync_with_stdio(0);
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)cin>>a[i][j];
    }
    cin>>x1>>y1>>x2>>y2;
    bfs(x1,y1);
}