Algorithmic Implementation series(6) Implementation of Quick_Sort

最新推荐文章于 2025-06-12 08:00:00 发布

jimodeyangguang

最新推荐文章于 2025-06-12 08:00:00 发布

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分类专栏： Algorithms implementations C++ 文章标签： algorithms implement

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本文介绍了一种使用C++实现的快速排序算法，包括元素交换、分区操作等关键步骤，并展示了如何通过递归调用完成整个数组的排序过程。

Compiler: gcc 4.7.3

C++ Standard: C++0x

OS:CentOS 6.3 x86

1 #include <iostream>
2
3 using namespace std;
4
5 //swap the ith element and the jth element in an array
6 void swap_elements(int ia[], const size_t i, const size_t j) {
7 if(i == j) { return; }
8 const int tmp = ia[i - 1];
9 ia[i - 1] = ia[j - 1];
10 ia[j - 1] = tmp;
11 }
12
13 const size_t partition(int ia[], const size_t p,const size_t r) {
14 //The value of variable x is the last element in array ia.
15 const int x = ia[r - 1];
16
17 //Variable i marks the position before the first element in
18 //array ia.
19 int i = p - 2;
20
21 //The for loop goes from the first element inclusive to one
22 //before the last element in array ia.
23 for(size_t j = p; j != r; ++j) {
24 if(ia[j - 1] <= x) {
25 ++i;
26 swap_elements(ia, i + 1, j);
27 }
28 }
29 swap_elements(ia, i + 2, r);
30 return i + 2;
31 }
32
33 void Quick_Sort(int ia[], const size_t p,const size_t r) {
34 if(p < r) {
35 const size_t q = partition(ia, p, r);
36 Quick_Sort(ia, p, q - 1);
37 Quick_Sort(ia, q + 1, r);
38 }
39 }
40
41 int main() {
42 int ia[] = {2, 32, 4, 6, -2, 4, 5, -55, -3, 55, 88};
43 const size_t size = sizeof(ia)/sizeof(int);
44
45 Quick_Sort(ia, 1, size);
46
47 for(size_t i = 0; i != size; ++i) {
48 cout << ia[i] << " ";
49 }
50 cout << endl;
51
52 return EXIT_SUCCESS;
53 }
54