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  1. import java.util.ArrayList;
  2. import java.util.Arrays;
  3. import java.util.Collections;
  4. import java.util.HashSet;
  5. import java.util.Iterator;
  6. import java.util.Scanner;
  7. import java.io.*;
  8.  
  9. public class Main {
  10. 	static int arr[];
  11. 	static int result[];
  12. 	static int N;
  13. 	static int M;
  14. 	static boolean visited[];
  15. 	static BufferedWriter bw;
  16. 	static HashSet<String> set = new HashSet();
  17.  
  18. 	public static void main(String[] args) throws IOException {
  19. 		// TODO Auto-generated method stub
  20. 		Scanner sc = new Scanner(System.in);
  21. 		bw = new BufferedWriter(new OutputStreamWriter(System.out));
  22. 		N = sc.nextInt();
  23. 		M = sc.nextInt();
  24. 		arr = new int[N];
  25. 		result = new int[M];
  26.  
  27. 		visited = new boolean[N];
  28.  
  29. 		for (int i = 0; i < N; i++) {
  30.  
  31. 			arr[i] = sc.nextInt();
  32.  
  33. 		}
  34.  
  35. 		Arrays.sort(arr);
  36. 		backtraking(0);
  37.  
  38. 		ArrayList list = new ArrayList(set);
  39. 		Collections.sort(list);
  40. 		Iterator it = list.iterator();
  41. 		while (it.hasNext()) {
  42. 			System.out.println(it.next());
  43. 		}
  44.  
  45. 	}
  46.  
  47. 	public static void backtraking(int index) throws IOException {
  48. 		if (index == M) {
  49. 			String a = "";
  50. 			for (int i = 0; i < M; i++) {
  51.  
  52. 				a += String.valueOf(result[i]) + " ";
  53.  
  54. 			}
  55. 			set.add(a);
  56.  
  57. 			return;
  58. 		}
  59. 		for (int i = 0; i < N; i++) {
  60.  
  61. 			if (visited[i])
  62. 				continue;
  63. 			visited[i] = true;
  64. 			result[index] = arr[i];
  65.  
  66. 			backtraking(index + 1);
  67. 			visited[i] = false;
  68.  
  69. 		}
  70. 	}
  71.  
  72. }
  73.  
  74.  
Success #stdin #stdout 0.06s 2184192KB
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https://ideone.com/IfzckQ
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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