求调！！BFS TLE#1 #3 #10 #11

求调！！ 感谢大佬！！

//2024-8-9 P1141 01迷宫 yishua by bong
#include <bits/stdc++.h>
using namespace std;
const int N = 2005;
const int M = 1e5;
int n, m;
int a[N][N];
int ans;
string s;
int rx, ry;
bool flag[N][N];

struct node {
    int xx, yy;
};

void bfs(int x, int y) {
    queue<node>q;
    q.push({x, y});
    while (!q.empty()) {
        int x = q.front().xx;
        int y = q.front().yy;
        q.pop();
        if (x < 1 || x > n)
            continue;
        if (y < 1 || y > n)
            continue;
        if (flag[x][y] == 1)
            continue;
        //if (a[x][y] == a[rx][ry])
        //  continue;
        flag[x][y] = 1;
        ans++;
        //rx = x, ry = y;
        if (a[x][y] != a[x + 1][y])
            q.push({x + 1, y});
        if (a[x][y] != a[x - 1][y])
            q.push({x - 1, y});
        if (a[x][y] != a[x][y + 1])
            q.push({x, y + 1});
        if (a[x][y] != a[x][y - 1])
            q.push({x, y - 1});
    }
    cout << ans << '\n';
    memset(flag, 0, sizeof(flag));
    ans = 0;
    return;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> s;
        for (int j = 0; j <= s.size() - 1; j++) {
            a[i][j + 1] = s[j];
        }
    }
    for (int i = 1; i <= m; i++) {
        int x, y;
        cin >> x >> y;
        bfs(x, y);
    }
    return 0;
}