백준 15663

package baekjoon.브루트포스.백트래킹;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main15663 {

   static int N, M;
   static int[] selected, nums, used;
   static StringBuilder sb = new StringBuilder();

   static void go(int k) {
      if (k == M + 1) {
         for (int i = 1; i <= M; i++) {
            sb.append(selected[i] + " ");
         }
         sb.append("\n");
      } else {
         int last_cand = 0;
         for (int i = 1; i <= N; i++) {
            if (used[i] == 1)
               continue;
            if (nums[i] == last_cand)
               continue;
            last_cand = nums[i];
            selected[k] = nums[i];
            used[i] = 1;
            go(k + 1);
            selected[k] = 0;
            used[i] = 0;
         }

      }
   }

   public static void main(String[] args) throws Exception {
      input();

      go(1);
      System.out.println(sb);
   }

   private static void input() throws IOException {
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      N = Integer.parseInt(st.nextToken());
      M = Integer.parseInt(st.nextToken());
      nums = new int[N + 1];
      used = new int[N + 1];
      selected = new int[M + 1];
      st = new StringTokenizer(br.readLine());
      for (int i = 1; i <= N; i++) {
         nums[i] = Integer.parseInt(st.nextToken());
      }
      Arrays.sort(nums, 1, N + 1);
   }

}