MergeSortTest

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MergeSort
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] arrayStart = new int[] { 5, 4, 1, 8, 90, 3};
            int[] newArray = someReturn(arrayStart);
            foreach (var item in someReturn(arrayStart))
            {
                Console.WriteLine(item);
            }

        }

        static int[] someReturn(int[] arrayForReturn)
        {
            int size = arrayForReturn.Length;

            if (arrayForReturn.Length == 2)
            {
                int a = 0;
                if (arrayForReturn[0] > arrayForReturn[1])
                {
                    a = arrayForReturn[0];
                    arrayForReturn[0] = arrayForReturn[1];
                    arrayForReturn[1] = a;
                    return arrayForReturn;
                }
                return arrayForReturn;
            }
            else
            {
                int[] firstArray = new int[size / 2];
                int[] secondArray = new int[size / 2];
                for (int i = 0; i < size / 2; i++)
                {
                    firstArray[i] = arrayForReturn[i];
                }
                for (int i = 0; i < size / 2; i++)
                {
                    secondArray[i] = arrayForReturn[i+size/2];
                }
                firstArray = someReturn(firstArray);
                secondArray = someReturn(secondArray);

                int k = 0;
                int j = 0;
                size = firstArray.Length + secondArray.Length;
                int[] outputArray = new int[size];
                for (int i = 0; i < size; i++)
                {
                    if (k == size / 2)
                        {
                            outputArray[i] = secondArray[j];
                            continue;
                        }
                    if (j == size / 2)
                    {
                        outputArray[i] = firstArray[k];
                        continue;
                    }
                    if (firstArray[k] < secondArray[j])
                    {
                        outputArray[i] = firstArray[k];
                        k++;
                    }
                    else
                    {
                        outputArray[i] = secondArray[j];
                        j++;
                    }
                }
                return outputArray;
            }
        }
    }
}