归并排序

  /// <summary>
    /// 归并排序。
    /// </summary>
    public static class MergedSorter
    {
        public static IEnumerable<int> Sort(IEnumerable<int> ary)
        {
            if (ary.Count() == 1)
                return ary;
            IEnumerable<int> lhalf = Sort(ary.Take(ary.Count() / 2));
            IEnumerable<int> rhalf = Sort(ary.Skip(ary.Count() / 2).Take(ary.Count() - ary.Count() / 2));
            return Merge(lhalf, rhalf);
        }

        private static int[] Merge(IEnumerable<int> lhalf, IEnumerable<int> rhalf)
        {
            int[] destAry = new int[lhalf.Count() + rhalf.Count()];
            int i = 0, j = 0, k = 0;
            //对比两个数组的元素。
            while (i < lhalf.Count() && j < rhalf.Count())
            {
                if (lhalf.ElementAt(i) < rhalf.ElementAt(j))
                    destAry[k++] = lhalf.ElementAt(i++);
                else
                    destAry[k++] = rhalf.ElementAt(j++);
            }
            //填充剩余的一个已排好序的数组。
            while (i < lhalf.Count())
            {
                destAry[k++] = lhalf.ElementAt(i++);
            }
            while (j < rhalf.Count())
            {
                destAry[k++] = rhalf.ElementAt(j++);
            }
            return destAry;
        }
    }
}

 上面是归并排序实现的方法，下面是调用方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ArraySortTest
{
    using ArraySort;

    class Program
    {
        static void Main(string[] args)
        {
            //int[] ary = { 4, 1, 3, 2, 16, 9, 10, 14, 8 };
            int[] ary = { 100, 38,45,78 ,123};
            foreach (int i in MergedSorter.Sort(ary))
            {
                Console.WriteLine(i.ToString());
            }
            Console.ReadKey();
        }
    }
}