[java] 백트래킹 중복제거 코드

import java.io.*;
import java.util.*;

public class Main{
    static int arr[];
    static boolean visit[];
    static int a,b;
    static StringBuilder sb;
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(br.readLine());
        a=Integer.parseInt(st.nextToken());
        b=Integer.parseInt(st.nextToken());
        arr=new int[b];
        visit=new boolean[a];
        sb=new StringBuilder();
        DFS(0,0);
        System.out.println(sb);


    }
    private static void DFS(int k,int depth) {
        if(depth==b) {
            for(int date:arr) {
                sb.append(date+" ");
            }
            sb.append("\n");
            return;
        }
        for(int i=k;i<a;i++) {

            arr[depth]=i+1;
            DFS(i+1,depth+1);
            
        }

    }
}