[Silver 3] 15655번 N과 M (6)

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

public class Main {
    public static int[] numbers;
    public static int[] ans;
    public static StringBuilder sb;
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] arr1 = br.readLine().split(" ");
        String[] arr2 = br.readLine().split(" ");
        int n = Integer.parseInt(arr1[0]); int m = Integer.parseInt(arr1[1]);
        numbers = new int[n]; ans = new int[m];
        sb = new StringBuilder();
        
        for(int i=0; i<n; i++) { numbers[i] = Integer.parseInt(arr2[i]); }
        
        Arrays.sort(numbers);
        calc(0, 0, n, m);
        
        System.out.println(sb);
    }
    
    public static void calc(int index, int selected, int n, int m) {
        if(selected==m) {
            for(int a : ans) { sb.append(String.valueOf(a)).append(" "); }
            
            sb.append("\n"); return;
        }
        
        if(index>=n) { return; }
        
        ans[selected] = numbers[index];
        calc(index+1, selected+1, n, m);
        calc(index+1, selected, n, m);
    }
}