Task4_MergeSort+Benchmark

using System;
using BenchmarkDotNet.Attributes;

namespace Task4C
{
    [MemoryDiagnoser]
    public class MergedSort
    {
        private int[] _numbers;

        private void Merge(int[] array, int lowIndex, int middleIndex, int highIndex)
        {
            var left = lowIndex;
            var right = middleIndex + 1;
            var tempArray = new int[highIndex - lowIndex + 1];
            var index = 0;

            while ((left <= middleIndex) && (right <= highIndex))
            {
                if (array[left] < array[right])
                {
                    tempArray[index] = array[left];
                    left++;
                }
                else
                {
                    tempArray[index] = array[right];
                    right++;
                }

                index++;
            }

            for (var i = left; i <= middleIndex; i++)
            {
                tempArray[index] = array[i];
                index++;
            }

            for (var i = right; i <= highIndex; i++)
            {
                tempArray[index] = array[i];
                index++;
            }

            for (var i = 0; i < tempArray.Length; i++)
            {
                array[lowIndex + i] = tempArray[i];
            }
        }

        private int[] MergeSort(int[] array, int lowIndex, int highIndex)
        {
            if (lowIndex < highIndex)
            {
                var middleIndex = (lowIndex + highIndex) / 2;
                MergeSort(array, lowIndex, middleIndex);
                MergeSort(array, middleIndex + 1, highIndex);
                Merge(array, lowIndex, middleIndex, highIndex);
            }

            return array;
        }

        [Benchmark]
        public void MergeSort()
        {
            MergeSort(_numbers, 0, _numbers.Length - 1);
        }

        [IterationSetup]
        public void MakeArray()
        {
            var number = new Random();
            var arr = new int[2000];
            for (var i = 0; i < arr.Length; i++) {
                arr[i] = number.Next();
            }

            _numbers = arr;
        }
    }
}