C#算法基础之递归排序

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

 namespace ConsolePractice
 {
     class CArray
     {
         private int[] arr;
         //数组大小
         private int upper;
         //下标
         private int numElements;

         /// <summary>
         /// 初始化数组参数
         /// </summary>
         /// <param name="size"></param>
         public CArray(int size)
         {
             arr = new int[size];
             upper = size - ;
             numElements = ;
         }

         /// <summary>
         /// 插入方法
         /// </summary>
         /// <param name="item">存储的数</param>
         public void Insert(int item)
         {
             arr[numElements] = item;
             numElements++;
         }

         /// <summary>
         /// 输出方法
         /// </summary>
         public void DisplayElements()
         {
             for (int i = ; i <= upper; i++)
             {
                 Console.Write(arr[i] + " ");
             }
             Console.WriteLine();
         }

         /// <summary>
         /// 清除数组
         /// </summary>
         public void Clear()
         {
             for (int i = ; i <= upper; i++)
             {
                 arr[i] = ;
             }
             numElements = ;
         }

         #region 递归排序算法
         /// <summary>
         /// 递归排序合并两个子集的方法
         /// </summary>
         /// <param name="tempArray">临时数组</param>
         /// <param name="lowp">子集1的下标</param>
         /// <param name="highp">子集2的下标，同时可以计算出子集1的长度</param>
         /// <param name="ubound">子集2的长度</param>
         public void Merge(int[] tempArray, int lowp, int highp, int ubound)
         {
             //主数组arr的初始下标位置
             int lbound = lowp;
             //子集1的长度
             int mid = highp - ;
             //主数组arr的长度
             int n = (ubound - lbound) + ;

             int j = ;
             //3个while的作用是合并子集1和子集2到临时的数组中
             while ((lowp <= mid) && (highp <= ubound))
             {
                 if (arr[lowp] < arr[highp])
                 {
                     tempArray[j] = arr[lowp];
                     lowp++;
                     j++;
                 }
                 else
                 {
                     tempArray[j] = arr[highp];
                     highp++;
                     j++;
                 }
             }
             //子集1还留有数值时
             while (lowp <= mid)
             {
                 tempArray[j] = arr[lowp];
                 j++;
                 lowp++;
             }
             //子集2还留有数值时
             while (highp <= ubound)
             {
                 tempArray[j] = arr[highp];
                 j++;
                 highp++;
             }

             //将临时数组存储的数值替换主数组的数值。
             for (j = ; j <= n - ; j++)
             {
                 arr[lbound + j] = tempArray[j];
             }

             this.DisplayElements();
         }

         /// <summary>
         /// 递归方法
         /// </summary>
         /// <param name="tempArray">临时数组</param>
         /// <param name="lbound">数组的最小下标</param>
         /// <param name="ubound">数组的最大下标</param>
         public void RecMergeSort(int[] tempArray, int lbound, int ubound)
         {
             if (lbound == ubound)
                 return;
             else
             {
                 //求出中间的下标
                 int mid = (int)(lbound + ubound) / ;
                 //子集1的递归
                 RecMergeSort(tempArray, lbound, mid);
                 //子集2的递归
                 RecMergeSort(tempArray, mid + , ubound);
                 //合并子集1和子集2
                 Merge(tempArray, lbound, mid + , ubound);
             }
         }

         /// <summary>
         /// 调用递归排序算法
         /// </summary>
         public void MergeSort()
         {
             int[] tempArray = new int[numElements];
             RecMergeSort(tempArray,,numElements-);
         }
         #endregion
     }

     class C_shape
     {
         static void Main()
         {
             CArray nums = new CArray();
             Random rnd = new Random();
             for (int i = ; i < ; i++)
             {
                 nums.Insert(rnd.Next(, ));
             }
             Console.WriteLine("Before sorting:");
             nums.DisplayElements();
             Console.WriteLine("During sorting:");
             nums.MergeSort();
             Console.WriteLine("After sorting:");
             nums.DisplayElements();
             Console.ReadKey();
         }
     }
 }

运行结果：