ZZULIOJ 1405: Red and Black，Java（BFS）

import java.io.*;
import java.util.*;
public class Main {
    static BufferedReader sc = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
    static int N = 30,n,m;
    static char [][]g = new char[N][N];
    public static int bfs(Pair p)
    {
        int []dx={-1,0,1,0},dy={0,1,0,-1};
        Queue Q=new linkedList<>();
        Q.offer(p);
        g[p.x][p.y]='#';
        int res=0;
        while(!Q.isEmpty())
        {
            Pair t=Q.poll();
            res++;
            for(int i=0;i<4;i++)
            {
                int x=t.x+dx[i],y=t.y+dy[i];
                if(x>=0&&x=0&&y