70分TLE求调

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1001;
char maze[MAXN][MAXN];
bool visited[MAXN][MAXN];
int n, m;
int dx[4] = {0, 1, 0, -1}; 
int dy[4] = {1, 0, -1, 0};

void bfs(int x, int y) {
    int qx[MAXN * MAXN], qy[MAXN * MAXN];
    int head = 0, tail = 1;
    qx[1] = x;
    qy[1] = y;
    visited[x][y] = true;
    int count = 1; 
    while (head < tail) {
        head++;
        for (int i = 0; i < 4; i++) {
            int nx = qx[head] + dx[i];
            int ny = qy[head] + dy[i];
            if (nx >= 1 && nx <= n && ny >= 1 && ny <= n && !visited[nx][ny] && maze[nx][ny] != maze[qx[head]][qy[head]]) {
                tail++;
                qx[tail] = nx;
                qy[tail] = ny;
                visited[nx][ny] = true;
                count++;
            }
        }
    }

    cout << count << endl;
}

int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> maze[i][j];
            visited[i][j] = false; 
        }
    }

    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        memset(visited, 0, sizeof(visited)); 
        bfs(x, y);
    }

    return 0;
}