using System;
using System.Linq;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
			int[] arr = { 1, 2, 3, 4 };
			IEnumerable<IEnumerable<int>> result = arr.Select(x => new List<int>() { x });
			for (int i = 1; i < arr.Length; i++)
			    result = result.SelectMany(x => arr.Except(x), (x, y) => x.Concat(new int[] { y }));
			foreach (var item in result)
			{
			    foreach (int i in item)
			        Console.Write(i + " ");
			    Console.WriteLine();
			}
        }
    }
}