Question

How to count the total of all pairs permutations in an array with C#

Answer 1

using System;

internal class Program
{
	public static void Main(string[] args)
	{
		int[] arr1 = new int[] {1, 8, 5};

		// The pairs are: (1, 8), (1, 5), (8, 1), (8, 5), (5, 1), (5, 8) 

		int total_pairs = arr1.Length * (arr1.Length - 1);
		Console.WriteLine("Total Pairs = " + total_pairs);

		int[] arr2 = new int[] {1, 8, 5, 2};

		// The pairs are: (1, 8), (1, 5), (1, 2), (8, 1), (8, 5), (8, 2), 
		//                (5, 1), (5, 8), (5, 2), (2, 1), (2, 8), (2, 5)

		total_pairs = arr2.Length * (arr2.Length - 1);
		Console.WriteLine("Total Pairs = " + total_pairs);
	}
}



/*
run:
  
Total Pairs = 6
Total Pairs = 12
  
*/

 

70+ SQL courses for beginners and professionals