查错

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1005;
char a[N][N];
int  n, m, vis[N][N], dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1}, qx, qy, l, sum[N * N], b[N][N];
struct node{
	int x, y;
};
bool check(int x, int y, int l1, int l2)
{
	if(x < 1 || x > n || y < 1 || y > n)
		return 1;
	else if(vis[x][y] || a[x][y] == a[l1][l2])
		return 1;
	return 0; 
}
void bfs()
{
	queue<node>q;
	b[qx][qy] = l;
	q.push({qx, qy});
	vis[qx][qy] = 1;
	while(q.size())
	{
		node t = q.front();
		q.pop();
		sum[l] ++;
		for(int i = 0 ;i < 4; ++ i)
		{
			int px = t.x + dx[i], py = t.y + dy[i];
			if(check(px, py, t.x, t.y))
				continue;
			vis[px][py] = 1;
			b[px][py] = l;
			q.push({px, py});
		}
	} 
	return ;
}
signed main()
{
	cin >> n >> m;
	for(int i = 1; i <= n; ++ i)
	{
		for(int j = 1; j <= n; ++ j)
		{
			cin >> a[i][j];
		}
	}
	for(int i =1 ;i <= n; ++ i)
	{
		for(int j = 1; j<= n; ++ j)
		{
			if(!vis[i][j])
			{
				int qx = i, qy = j, l = l + 1;
				bfs();
			}
		}
	}
	while(m --)
	{
		int x, y;
		cin >> x >> y;
		cout << sum[b[x][y]] << "\n";
	}
	return 0;
}