Console Program to calculate inversions in an array.

gistfile1.cs

using System;
using System.IO;
using System.Linq;

namespace CountingInversions
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var input = InputGetter.GetInput(@"C:\InputFile.txt");
			int[] sortedArray;
			Console.WriteLine("Please wait counting inversions...");
			var result = CountAndSort(input, out sortedArray);
			Console.WriteLine(result);
		}		
				
		static Int64 CountAndSort(int[] input, out int[] output) 
		{
			Int64 count = 0;
			
			if(input.Length == 1) 
			{
				output = input;
				return count;
			}
			
			int[] left, right;
			int leftLength = input.Length/2; 
			count += CountAndSort(input.Take(leftLength).ToArray(), out left);
			count += CountAndSort(input.Skip(leftLength).ToArray(), out right);			
			count += CountSplitAndMerge(left, right, out output);
						
			return count;
		}
		
		static Int64 CountSplitAndMerge(int[] left, int[] right, out int[] output)
		{
			Int64 count = 0;
			int i = 0, j = 0, l = left.Length + right.Length;
			output = new int[l];
			
			for(int k = 0; k < l; k++)
			{
				if(i < left.Length && (j >= right.Length || left[i] < right[j]))
				{
					output[k] = left[i];
					i++;
				}
				else 
				{
					output[k] = right[j];
					j++;
					count+=(left.Length-i);
				}
			}
			
			return count;
		}
	}
	
	
	
	static class InputGetter
	{
		public static int[] GetInput(string path)
		{
			var input = File.ReadAllLines(path);
			var result = new int[input.Length];
			for(int i = 0, l = input.Length; i < l; i++)
			{
				result[i] = int.Parse(input[i]);
			}
			return result;
		}
	}
}