BEAKJOON JAVA ALGORITHM #9019(DSLR)

https://www.acmicpc.net/problem/9019

import java.util.LinkedList; import java.util.Queue; import java.util.Scanner; public class a9019 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int num = sc.nextInt(); for(int i=0; i<num; i++) { int a = sc.nextInt(); int b = sc.nextInt(); boolean[] check = new boolean[10001]; int[] dist = new int[10001]; char[] how = new char[10001]; int[] from = new int[10001]; check[a] = true; dist[a] = 0; from[a] = -1; Queue<Integer> q = new LinkedList<Integer>(); q.add(a); while(!q.isEmpty()) { int now = q.remove(); int next = (now*2) % 10000; if(check[next] == false) { q.add(next); check[next] = true; dist[next] = dist[now] + 1; from[next] = now; how[next] = 'D'; } next = now - 1; if(next == -1) { next = 9999; } if(check[next] == false) { q.add(next); check[next] = true; dist[next] = dist[now] + 1; from[next] = now; how[next] = 'S'; } next = (now%1000)*10 + (now/1000); if(check[next] == false) { q.add(next); check[next] = true; dist[next] = dist[now] + 1; from[next] = now; how[next] = 'L'; } next = (now%10)*1000 + (now/10); if(check[next] == false) { q.add(next); check[next] = true; dist[next] = dist[now] + 1; from[next] = now; how[next] = 'R'; } } StringBuilder s = new StringBuilder(); while(b != a) { s.append(how[b]); b = from[b]; } for(int p=s.length(); p>0; p--) { System.out.print(s.charAt(p-1)); } System.out.println(); } } }