0分MLE求助

#include<bits/stdc++.h>
using namespace std;
int mapp[10000][10010];
int qx[10010],qy[10010];
int dx[16]={-4,-3,-2,-1,1,2,3,4,0,0,0,0,0,0,0,0};
int dy[16]={0,0,0,0,0,0,0,0,-4,-3,-2,-1,1,2,3,4};
int vis[10010][10010];
int main()
{
    int n,m;
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        string s;
        cin>>s;
        for(int j=0;j<s.size();j++)
        {
            mapp[i][j+1]=s[j]-48;
        }
    }
    while(m--)
    {
        int stx,sty,ans=0;
        memset(qx,0,sizeof(qx));
        memset(qy,0,sizeof(qy));
        memset(vis,0,sizeof(vis));
        cin>>stx>>sty;
        int front=-1,tail=0;
        qx[0]=stx,qy[0]=sty;
        while(front<tail)
        {
            front++;
            int tx=qx[front],ty=qy[front];
            for(int i=0;i<=15;i++)
            {
                int rx=tx+dx[i];
                int ry=ty+dy[i];
                if(rx>=1&&rx<=n&&ry>=1&&ry<=n&&vis[rx][ry]==0&&mapp[rx][ry]==!(mapp[tx][ty]))
                {
                    vis[rx][ry]=1;
                    ans++;
                    tail++;
                    qx[tail]=rx;
                    qy[tail]=ry;
                }
            }
        }
        cout<<ans<<endl;
    }
}