3 TLE

#include<bits/stdc++.h>
using namespace std;

const int N=1e3+10;
int n,m;
bool a[N][N];

int _visit[N][N];

int read() {
  int x = 0, w = 1;
  char ch = 0;
  while (ch < '0' || ch > '9') {  
    if (ch == '-') w = -1;       
    ch = getchar();               
  }
  while (ch >= '0' && ch <= '9') {  
    x = x * 10 + (ch - '0');  
    ch = getchar();  
  }
  return x * w;  
}
void write(int x) {

  if (x > 9) write(x / 10);  
  putchar(x % 10 + '0');  
}

int bfs(int x,int y){

    int cnt=0;
    bool vis[N][N]={0};
    queue<pair<int,int>>q,que;
    q.push({x,y});
    que.push({x,y});
    vis[x][y]=1;
    while(!q.empty()){
        pair<int,int> flag=q.front();
        q.pop();
        cnt++;
        int i=flag.first;
        int j=flag.second;
        if(i-1>0&&a[i-1][j]==!a[i][j]&&!vis[i-1][j]){
            q.push({i-1,j});
            que.push({i-1,j});
            vis[i-1][j]=1;
        }
        if(i+1<=n&&a[i+1][j]==!a[i][j]&&!vis[i+1][j]){
            q.push({i+1,j});
            que.push({i+1,j});
            vis[i+1][j]=1;
        }
        if(j-1>0&&a[i][j-1]==!a[i][j]&&!vis[i][j-1]){
            q.push({i,j-1});
            que.push({i,j-1});
            vis[i][j-1]=1;
        }
        if(j+1<=n&&a[i][j+1]==!a[i][j]&&!vis[i][j+1]){
            q.push({i,j+1});
            que.push({i,j+1});
            vis[i][j+1]=1;
        }
    }
    while(!que.empty()){
        int i=que.front().first,j=que.front().second;
        _visit[i][j]=cnt;
        que.pop();
    }
    return cnt;
}

signed main(){
//  ios::sync_with_stdio(false);
//  cin.tie(NULL);
//  cout.tie(NULL);
    cin>>n>>m;
    for(int j=1;j<=n;j++){
        for(int i=1;i<=n;i++){
            char s;
            cin>>s;
            if(s=='0'){
                a[j][i]=0;
            }           
            else a[j][i]=1;
        }
    }
    for(int i=1;i<=m;i++){
        int x,y;
        x=read();
        y=read();
        if(_visit[x][y]!=0){
            write( _visit[x][y]);
            cout<<"\n";
        }
        else {
            cout<<bfs(x,y)<<"\n";
        }
    }
    return 0;
}