Сортировка массива по возрастанию модулей разности соседей

using System;

namespace example
{
    class Program
    {
        public static void Main(string[] args)
        {
            int[] arr = { 12, 0, 5, 7, 6, -11, -2, -30, 8, 7 };

            ShowArray(arr);
            SortAbs(arr);
            ShowArray(arr);

            Console.ReadKey();
        }

        public static void ShowArray(int[] arr)
        {
            foreach (var a in arr) Console.Write(a + " ");
            Console.WriteLine();
        }

        public static void SortAbs(int[] arr)
        {
            int size = arr.Length;
            int last = LastElement(arr);
            int temp;
            int next;

            if (arr[size - 1] != last)
            {
                for (int k = 0; k < size; k++)
                {
                    if (arr[k] == last)
                    {
                        temp = arr[size - 1];
                        arr[size - 1] = arr[k];
                        arr[k] = temp;
                        break;
                    }
                }
            }

            for (int n = size - 2; n >= 0; n--)
            {
                next = NextElement(arr, n);

                if (arr[n] != next)
                {
                    for (int t = 0; t < size; t++)
                    {
                        if (arr[t] == next)
                        {
                            temp = arr[n];
                            arr[n] = arr[t];
                            arr[t] = temp;
                            break;
                        }
                    }
                }
            }
        }

        public static int NextElement(int[] arr, int stopIndex)
        {
            int max = 0;
            int temp;
            int next = arr[stopIndex];

            for (int n = stopIndex; n >= 0; n--)
            {
                temp = Math.Abs(arr[n] - arr[stopIndex + 1]);

                if (temp > max)
                {
                    max = temp;
                    next = arr[n];
                }

                if (temp == Int32.MaxValue) break;
            }

            return next;
        }

        public static int LastElement(int[] arr)
        {
            int max = 0;
            int temp;
            int size = arr.Length;
            bool flag = false;
            int last = arr[size - 1];

            for (int n = 0; n < size; n++)
            {
                for (int m = 0; m < size; m++)
                {
                    if (n == m) continue;

                    temp = Math.Abs(arr[m] - arr[n]);

                    if (temp > max)
                    {
                        max = temp;
                        last = arr[m];
                    }

                    if (temp == Int32.MaxValue)
                    {
                        flag = true;
                        break;
                    }
                }
                if (flag) break;
            }

            return last;
        }
    }
}