1 static void Main(string[] args)
2 {
3
4 Console.WriteLine("************快速排序*****************");
5 int[] list = new int[] { 4, 7, 6, 5, 3, 2, 8, 1 };
6 QuickSort qs = new QuickSort();
7 qs.quikSort(list, 0, list.Length - 1);
8 for (int i = 0; i < list.Length; i++)
9 {
10 Console.WriteLine("第{0}位是{1}", i + 1, list[i]);
11 }
12 // Console.WriteLine(list);
13
14 Console.ReadKey();
15 } 68
69
70 //递归快速排序法
71 public class QuickSort
72 {
73 //快速排序
74 public void quikSort(int[] arr, int startIndex, int endIndex)
75 {
76 //递归结束条件 startIndex>endIndex
77 if (startIndex >= endIndex)
78 {
79 return;
80 }
81
82 //得到基准元素的位置
83 int pivotIndex = partiton(arr, startIndex, endIndex);
84
85 //根据基准元素，分成两部分递归排序
86 quikSort(arr, startIndex, pivotIndex - 1);
87 quikSort(arr, pivotIndex + 1, endIndex);
88 }
89
//指针交换法
90 private static int partiton(int[] arr, int startIndex, int endIndex)
91 {
92 //取第一个位置的元素作为基准元素
93 int pivot = arr[startIndex];
94 int left = startIndex;
95 int right = endIndex;
96
97 while (left != right)
98 {
99 //控制right指针比较并左移
100 while (left < right && arr[right] > pivot)
101 {
102 right--;
103 }
104
105 //控制right指针比较并右移
106 while (left < right && arr[left] <= pivot)
107 {
108 left++;
109 }
110
111 //交换left和right指向的元素
112 if (left < right)
113 {
114 int p = arr[left];
115 arr[left] = arr[right];
116 arr[right] = p;
117 }
118 }
119
120 //pivoe和指针重合点交换
121 int s = arr[left];
122 arr[left] = arr[startIndex];
123 arr[startIndex] = s;
124
125 return left;
126 }
127
//挖坑法
private static int partiton1(int[] arr, int startIndex, int endIndex)
{
// 4, 7, 6, 5, 3, 2, 8, 1
//获取第一个位置的元素作为基准元素
int pivot = arr[startIndex]; //4
int left =startIndex; //0
int right = endIndex; //7
//坑的位置，初始等于pivot的位置
int index = startIndex; //0
//大循环在左右指针重合或交错时结束
while (right >= left)
{
//right指针从右向左进行比较
while (right >= left)
{
int a = arr[right];
if (arr[right] < pivot)
{
int s = arr[right];
int t = arr[left];
arr[left] = arr[right];
index = right;
left++;
break;
}
right--;
}
//left指针从左向右进行比较
while (right > left)
{
if (arr[left] >= pivot)
{
int a = arr[right];
int b = arr[left];
arr[right] = arr[left];
index = left;
right--;
break;
}
left++;
}
}
arr[index] = pivot;
return index;
}
128 }
