dalao帮看一下QAQ，WA了第二个点。。。

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
const int MAXN=2001;
int n,m,ans=0,d=0;
int f[MAXN][MAXN];
int book[MAXN][MAXN];
int cnt[5000001]={0};
int xx[5]={0,1,0,-1,0};
int yy[5]={0,0,1,0,-1};
bool vist[MAXN][MAXN];
queue<int>q;
queue<int>p;
void bfs(int sx,int sy)
{
    int x,y,nx,ny;
    book[sx][sy]=d;
    vist[sx][sy]=true;
    q.push(sx);
    p.push(sy);
    while(!q.empty())
    {
        x=q.front();
        y=p.front();
        q.pop();
        p.pop();
        for(int t=1;t<=4;t++)
        {
            nx=x+xx[t];ny=y+yy[t];
            if(nx>=1&&nx<=n&&ny>=1&&ny<=n&&f[nx][ny]!=f[x][y]&&!vist[nx][ny])
            {
                q.push(nx);
                p.push(ny);
                vist[nx][ny]=true;
                ans++;
                book[nx][ny]=d;
            }
        }
    }
}
int main()
{
    //freopen("text.in","r",stdin);
//	freopen("text.out","w",stdout);
    memset(vist,false,sizeof(vist));
    memset(book,0,sizeof(0));
    scanf("%d %d\n",&n,&m);
    for(int i=1;i<=n;i++)
    {
        char ch;
        for(int j=1;j<=n;j++)
        {
            scanf("%c",&ch);
            f[i][j]=ch-'0';
        }
        scanf("\n");
    }
    for(int i=1;i<n;i++)
    {
        for(int j=1;j<n;j++)
        {
            if(book[i][j]==0)
            {
                ans=0;
                d++;
                bfs(i,j);
                cnt[d]=ans+1;
            }
        }
    }
    for(int i=1;i<=m;i++)
    {
        int a,b;
        scanf("%d %d\n",&a,&b);
        printf("%d\n",cnt[book[a][b]]);	
    }
    return 0;
}