P15654_순열.java

package net.acmicpc.순열조합;

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

public class P15654_순열 {
  static int M;
  static int N;
  static boolean[] checked;
  static int[] numbers;
  static int[] result;

  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] NM = br.readLine().split(" ");
    N = Integer.parseInt(NM[0]);
    M = Integer.parseInt(NM[1]);

    numbers = new int[N];
    checked = new boolean[N];
    result = new int[M];
    String[] num = br.readLine().split(" ");
    for (int i = 0; i < N; ++i) {
      numbers[i] = Integer.parseInt(num[i]);
    }

    Arrays.sort(numbers);
    permutation(0);
  }

  private static void permutation(int index) {
    if (index == M) {
      for (int i = 0; i < result.length; ++i) {
        System.out.print(result[i] + " ");
      }
      System.out.println();
      return;
    }
    for (int i = 0; i < N; ++i) {
      if (!checked[i]) {
        result[index] = numbers[i];
        checked[i] = true;
        permutation(index + 1);
        checked[i] = false;
      }
    }
  }
}