洛谷 P1443 马的遍历 Java

import java.util.*;
import java.io.*;
 
public class Main{
 
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
    static boolean[][] judge;
    static int[][] distance;
    static int[] X = new int[] {-1,-2,-2,-1,1,2,2,1};
    static int[] Y = new int[] {2,1,-1,-2,2,1,-1,-2};
    static int n,m,x,y;
 
    public static void main(String[] args) throws IOException {
    	String[] S = br.readLine().split(" ");
    	n = Integer.parseInt(S[0]);
    	m = Integer.parseInt(S[1]);
    	x = Integer.parseInt(S[2]);
    	y = Integer.parseInt(S[3]);
    	distance = new int[n+1][m+1];
    	judge = new boolean[n+1][m+1];
    	for(int i = 1 ; i <= n ; i++) {
    		for(int j = 1 ; j <= m ; j++) {
    			distance[i][j] = -1;
    		}
    	}
    	distance[x][y] = 0;
    	BFS();
    	for(int i = 1 ; i <= n ; i++) {
    		for(int j = 1 ; j <= m ; j++) {
    			System.out.printf("%-5d",distance[i][j]);
    		}
    		System.out.println();
    	}
        out.flush();
        out.close();
        br.close();
    }
    
    private static void BFS() {
    	Point begin = new Point();
    	begin.x = x;
    	begin.y = y;
    	Deque deque = new LinkedList<>();
    	deque.offer(begin);
    	while(!deque.isEmpty()) {
    		Point p = deque.poll();
    		judge[p.x][p.y] = true;
    		for(int i = 0 ; i < 8 ; i++) {
    			int a = p.x + X[i];
    			int b = p.y + Y[i];
    			Point node;
    			if(a >= 1 && a <= n && b >= 1 && b<= m && !judge[a][b]) {
    				if(distance[a][b] == -1) {
    					distance[a][b] = distance[p.x][p.y] + 1;
    				}
    				else {
    					distance[a][b] = Math.min(distance[a][b],distance[p.x][p.y]+1);
    				}
    				node = new Point();
    				node.x = a;
    				node.y = b;
    				judge[a][b] = true;
    				deque.offer(node);
    			}
    		}
    	}
    }
}
 
class Point{
	int x;
	int y;
}