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  1. using System;
  2. using System.Linq;
  3. using System.Collections.Generic;
  4.  
  5. namespace ConsoleApp1
  6. {
  7.     class Program
  8.     {
  9.         static IEnumerable<IEnumerable<int>> SelectNElements(int[] arr, int n)
  10.         {
  11.             IEnumerable<IEnumerable<int>> result = arr.Select(x => new List<int>() { x });
  12.             for (int i = 1; i < n; i++)
  13.                 result = result.SelectMany(x => arr.Where(y => y > x.Max()), (x, y) => x.Concat(new int[] { y }));
  14.             return result;
  15.         }
  16.         static void Main(string[] args)
  17.         {
  18.             int[] arr = { 1, 2, 3, 4 };
  19.             for (int i = 1; i <= arr.Length; i++)
  20.             {
  21.                 var result = SelectNElements(arr, i);
  22.                 foreach (var item in result)
  23.                 {
  24.                     foreach (int x in item)
  25.                         Console.Write(x + " ");
  26.                     Console.WriteLine();
  27.                 }
  28.             }
  29.         }
  30.     }
  31. }
  32.  
Success #stdin #stdout 0.04s 16184KB
comments (?)
stdin
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Standard input is empty
stdout
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1 
2 
3 
4 
1 2 
1 3 
1 4 
2 3 
2 4 
3 4 
1 2 3 
1 2 4 
1 3 4 
2 3 4 
1 2 3 4
https://ideone.com/MqlZzp
language:
C# (gmcs 5.20.1)
created:
6 years ago
visibility:
public

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