#include <iostream>
#include <cstring>
using namespace std;

const int N = 1010, M = 1e5 + 10;
int q[N][N], n, m, cnt, lin[N * N+10];
int idx = 1;
bool st[N][N];

int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dfs(int x, int y)
{
	st[x][y] = true;
	int sum = 1;
	lin[n * x + y] = idx;
	for (int i = 0; i < 4; i++)
	{
		int a = x + dx[i], b = y + dy[i];
		if (a > 0 && a <= n && b > 0 && b <= n && (q[a][b] == !q[x][y]) && st[a][b] == false)
		{
			int s = dfs(a, b);
			sum += s;
		}
	}
	cnt = max(cnt, sum);
	return sum;
}

int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++)
	{
		string s;
		cin >> s;
		for (int j = 1; j <= n; j++)
		{
			q[i][j] = s[j-1] - '0';
		}
		getchar();
	}
	int res[M];
	while (m--)
	{
		int i, j;
		cin >> i >> j;
		if(lin[n*i+j] == 0)
		{
			cnt = 0;
			memset(st, false, sizeof(st));
			dfs(i, j);
			res[idx++] = cnt;
			cout << cnt << endl;
		}
		else
		{
			cout << res[lin[n * i + j]] << endl;
		}
	}

	return 0;
}

是哪里优化的还不够吗？