七十分不会优化，求大佬帮助

#include <iostream>
#include <queue>
#include <cstring>

#define x first
#define y second

using namespace std;

const int N = 1001;
const int M = 100001;

typedef pair<int, int> PII;

char mp[N][N];
bool st[N][N];
PII ask[M];
queue<PII> q;
int cnt, n, m;

int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};

bool Try(char ch1, char ch2) {
        if(ch1 == '0' && ch2 == '1') return true;
        if(ch1 == '1' && ch2 == '0') return true;
        return false;
}

void init(void) {
        cnt = 1;
        memset(st, false, sizeof(st));
        while(!q.empty()) q.pop();
}

void bfs(int sx, int sy) {
        q.push({sx, sy});
        st[sx][sy] = true;

        while(!q.empty()) {
                auto t = q.front();
                q.pop();

                for(int i = 0; i < 4; i++) {
                        int a = t.x + dx[i];
                        int b = t.y + dy[i];

                        if(a > n || a < 1 || b > n || b < 1) continue;
                        if(st[a][b]) continue;

                        if(Try(mp[t.x][t.y], mp[a][b])) {
                                st[a][b] = true;
                                q.push({a, b});
                                cnt++;
                        }
                }
        }
}

int main(void) {
        cin >> n >> m;
        for(int i = 1; i <= n; i++) {
                for(int j = 1; j <= n; j++) {
                        cin >> mp[i][j];
                }
        }
        for(int i = 1; i <= m; i++) {
                init();
                int t1, t2;
                cin >> t1 >> t2;
                bfs(t1, t2);
                cout << cnt << endl;
        }

        return 0;
}