测试点3超时

,#3TLE,其余均通过，求助大佬

#include<iostream>
#include<queue>
#include<memory.h>
using namespace std;

const int N=1005;
char map[N][N];
int ans[100005];
int isqe[N][N];
int flag[N][N];
int d1[] = {-1,0,1,0};
int d2[] = {0,-1,0,1};
int n,m,num;
struct node{
    int x,y;
};

void bfs(int x,int y)
{
    queue<node> qe;
    node front = {x,y};
    qe.push(front);
    flag[x][y] = num;
    ans[num] = 1;
    isqe[x][y] = 1;
    while(!qe.empty()){
        node top = qe.front();
        qe.pop();
        for(int k=0;k<=3;k++){
            int newx = top.x+d1[k];
            int newy = top.y+d2[k];
            if(newx>=0&&newx<n&&newy>=0&&newy<n&&map[newx][newy]!=map[top.x][top.y]&&!isqe[newx][newy]){
                ans[num]++;
                flag[newx][newy] = num;
                isqe[newx][newy] = 1;
                qe.push({newx,newy});
            }
        }
    }
}

int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++){
        cin>>map[i];
    }
    for(int i=1;i<=m;i++){
        int x,y;
        cin>>x>>y;
        if(!flag[x-1][y-1]){
            memset(isqe,0,sizeof isqe);
            bfs(x-1,y-1);
            num++;
        }
        cout<<ans[flag[x-1][y-1]]<<endl;
    }
    return 0;
}