Quicksort

    public static int Partition (int[] arr, int left, int right)
    {
        int pivot = arr[left];
        while(true)
        {
            while(arr[left] < pivot)
            left++;

            while(arr[right] > pivot)
            right--;

            if (arr[left] == pivot && arr[right] == pivot)
            left++;

            if(left < right)
            {
                int temp = arr[right];
                arr[right] = arr[left];
                arr[left] = temp;
            }
            else
            return right;
        }
    }


    public static void QuickSort (int[] arr, int left, int right)
    {
        if(left < right)
        {
            int pivot = Partition(arr, left, right);

            if (pivot > 1)
            {
                QuickSort(arr, left, pivot - 1);
            }
            if (pivot + 1 < right)
            {
                QuickSort(arr,pivot + 1,right);
            }
        }
    }

    public static void Main()
    {
        int[] myArr = { 9, 8, 6, 5, 4, 123, 131};

        QuickSort(myArr, 0, myArr.Length - 1);
        for(int i = 0; i < myArr.Length; i++)
        {
            Console.WriteLine(myArr[i]);
        }
    }