C#算法基础之快速排序

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 - 1;
            numElements = 0;
        }

        /// <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 = 0; i <= upper; i++)
            {
                Console.Write(arr[i] + " ");
            }
            Console.WriteLine();
        }

        /// <summary>
        /// 清除数组
        /// </summary>
        public void Clear()
        {
            for (int i = 0; i <= upper; i++)
            {
                arr[i] = 0;
            }
            numElements = 0;
        }

        #region 快速排序算法
        /// <summary>
        /// 快速排序算法
        /// </summary>
        public void QSort()
        {
            RecQSort(0, numElements - 1);
        }

        public void RecQSort(int first, int last)
        {
            if ((last - first) <= 0)
                return;
            else
            {
                int part = this.Partition(first, last);
                RecQSort(first, part - 1);
                RecQSort(part + 1, last);
            }
        }

        public int Partition(int first, int last)
        {
            int pivotVal = arr[first];
            int theFirst = first;
            bool okSide;
            first++;
            do
            {
                okSide = true;
                while (okSide)
                {
                    if (arr[first] > pivotVal)
                        okSide = false;
                    else
                    {
                        first++;
                        okSide = (first <= last);
                    }
                }
                okSide = true;
                while (okSide)
                {
                    if (arr[last] <= pivotVal)
                        okSide = false;
                    else
                    {
                        last--;
                        okSide = (first <= last);
                    }
                }
                if (first < last)
                {
                    Swap(first, last);
                    this.DisplayElements();
                    first++;
                    last--;
                }

            } while (first <= last);
            Swap(theFirst, last);
            this.DisplayElements();
            return last;
        }

        public void Swap(int item1, int item2)
        {
            int temp = arr[item1];
            arr[item1] = arr[item2];
            arr[item2] = temp;
        }
        #endregion
    }

    class C_shape
    {
        static void Main()
        {
            CArray nums = new CArray(10);
            Random rnd = new Random(100);
            for (int i = 0; i < 10; i++)
            {
                nums.Insert(rnd.Next(0, 100));
            }
            Console.WriteLine("Before sorting:");
            nums.DisplayElements();
            Console.WriteLine("During sorting:");
            nums.QSort();
            Console.WriteLine("After sorting:");
            nums.DisplayElements();
            Console.ReadKey();
        }
    }
}