Quick sort in C#

Quick Sort:
It is a divide and conquer algorithm which relies on a partition operation, i.e., to partition an array, choose an element called a pivot, move all smaller elements before the pivot, and move all greater elements after it. This can be done efficiently in linear time and in-place. Later, recursively sort the lesser and greater sublists.

using System;

using System.Collections.Generic;

using System.Text;

using System.Collections;

namespace DataStructureAlgoriths

{

    class Sort

        public void Quicksort()

        {

            long[] inputArray = new long[] { 4, 9, 8, 6, 3, 2, 1 };

            int left = 0;

            int right = inputArray.Length - 1;

            long[] final = InternalQuickSort(inputArray, left, right);

            foreach (var item in final)

            {

                Console.WriteLine(item);

            }

        }

        private long[] InternalQuickSort(long[] inputArray, int left, int right)

        {

            int pivotNewIndex = Partition(inputArray, left, right);

            long pivot = inputArray[(left + right) / 2];

            if (left < pivotNewIndex - 1)

                InternalQuickSort(inputArray, left, pivotNewIndex - 1);

            if (pivotNewIndex < right)

                InternalQuickSort(inputArray, pivotNewIndex, right);

            return inputArray;

        }

        private int Partition(long[] inputArray, int left, int right)

        {

            int i = left, j = right;

            long pivot = inputArray[(left + right) / 2];

            while (i <= j)

            {

                while (inputArray[i] < pivot)

                    i++;

                while (inputArray[j] > pivot)

                    j--;

                if (i <= j)

                {

                    SwapWithTemp(ref inputArray[i], ref inputArray[j]);

                    i++; j--;

                }

            }

            return i;

        }

        private void SwapWithTemp(ref long valOne, ref long valTwo)

        {

            long temp = valOne;

            valOne = valTwo;

            valTwo = temp;

        }

}

}

using System;

using System.Collections.Generic;

using System.Text;

namespace DataStructureAlgoriths

{

    class Program

    {

        static void Main(string[] args)

        {

            Sort s = new Sort();

            s.Quicksort();

            Console.ReadLine();

        }

    }

}