CodeForces

题目链接

BFS 注意起点和终点相同的情况

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main{
    static String s0,s1;
    static String[] str = {"LU","U","RU","R","RD","D","LD","L"};
    static int[][] next = {{-1,1},{0,1},{1,1},{1,0},{1,-1},{0,-1},{-1,-1},{-1,0}};
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()){
            s0 = sc.next();
            s1 = sc.next();
            bfs();
        }
    }
    public static void bfs(){
        int x0 = Integer.valueOf(s0.charAt(0)-'a');
        int y0 = Integer.valueOf(s0.substring(1));
        int x1 = Integer.valueOf(s1.charAt(0)-'a');
        int y1 = Integer.valueOf(s1.substring(1));
        Queue<Node> queue = new LinkedList<>();
        boolean[][] flag = new boolean[10][10];
        flag[x0][y0] = true;
        queue.add(new Node(x0,y0,0,""));
        if(x0==x1&&y0==y1){
            System.out.println(0);
            return;
        }
        while(queue.size()>0){
            Node no = queue.poll();
            int x = no.x;
            int y = no.y;
            int s = no.s;
            String b = no.book;
            for(int i=0;i<8;i++){
                int ts = s+1;
                int tx = x+next[i][0];
                int ty = y+next[i][1];
                String tb = b+str[i]+"
";
                if(tx<0||tx>=8||ty<1||ty>8) continue;
                if(flag[tx][ty]) continue;
                flag[tx][ty] = true;
                if(tx==x1&&ty==y1){
                    System.out.println(ts);
                    System.out.println(tb);
                    return;
                }
                queue.add(new Node(tx,ty,ts,tb));
            }
        }
    }
}
class Node{
    int x,y,s;
    String book;
    Node(int x,int y,int s,String book){
        this.x = x;
        this.y = y;
        this.s = s;
        this.book = book;
    }
}