C#でクイックソートの練習

QuickSort.cs

using System;

namespace QuickSort
{
	class MainClass
	{
		private static void quickSortInternal<Type>(Type[] array, int left, int right, Func<Type, Type, int> compare)
		{
			if (left >= right)
			{
				return;
			}

			var i = left;
			var j = right;
			var pivot = array[i];

			while (true)
			{
				while (i < right && compare(pivot, array[i]) < 0)
				{
					i++;
				}
				while (j >= left && compare(pivot, array[j]) > 0)
				{
					j--;
				}
				if (i >= j)
				{
					break;
				}
				var tmp = array[i];
				array[i] = array[j];
				array[j] = tmp;
				i++;
				j--;
			}
			quickSortInternal(array, left, i - 1, compare);
			quickSortInternal(array, j + 1, right, compare);
		}

		public static Type[] QuickSort<Type>(Type[] array, Func<Type, Type, int> compare)
		{
			var buff = new Type[array.Length];
			array.CopyTo(buff, 0);
			quickSortInternal(buff, 0, buff.Length - 1, compare);
			return buff;
		}

		public static void Main(string[] args)
		{
			int[] data = { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9 };
			Console.WriteLine("Data: {0}", String.Join(" ", data));

			var asc = QuickSort(data, (a, b) => (a == b) ? 0 : (a < b) ? 1 : -1);
			Console.WriteLine("Asc:  {0}", String.Join(" ", asc));

			var desc = QuickSort(data, (a, b) => (a == b) ? 0 : (a > b) ? 1 : -1);
			Console.WriteLine("Desc: {0}", String.Join(" ", desc));
		}
	}
}