算法篇

我是一个个人小开发，博客只供自己记录一些技能，以免忘记。勿喷

 

 

 

 

快速排序实现

 1 #include <iostream>
 2 #include <vector>
 3 
 4 using namespace std;
 5 
 6 
 7 void Quicksort(vector<int> &q,int l,int r)
 8 {
 9     if( l >= r) return;
10     int i = l - 1 , j = r + 1 , x = q[( l + r ) / 2] ;
11     while( i < j )
12     {
13         do i++; while (q[i] < x);
14         do j--; while (q[j] > x);
15         if(i < j ) swap(q[i],q[j]);
16     }
17     Quicksort(q,l,j);Quicksort(q,j+1,r);
18 }
19 
20 void Quicksort1(vector<int> &q,int l,int r)
21 {
22     if( l >= r) return;
23     int i = l - 1 , j = r + 1 , x = q.at(( l + r ) / 2) ;
24     while( i < j )
25     {
26         do i++; while (q.at(i) < x);
27         do j--; while (q.at(j) > x);
28         if(i < j ) swap(q.at(i),q.at(j));
29     }
30     Quicksort1(q,l,j);Quicksort1(q,j+1,r);
31 }
32 
33 
34 int main(int argc,char **argv)
35 {
36     //vector<int> p = {15,19,2,5,17,20,1,5,8,8,3,6,4};
37     vector<int> p = {4,1,1,1,1,5,6};
38 
39     for(auto z : p ) cout << z << "    , ";
40     cout << endl <<"======================|========================"<< endl;
41 
42 
43     vector<int> a(p);
44     Quicksort1(a,0,a.size() - 1 );
45     for(auto z : a ) cout << z << "    , ";
46     cout << endl <<"=============================================="<< endl;
47 
48     return 0;
49 }

数据多的时候比冒泡快。所以理论上是快速排序快

还有vector使用[]重载的时候不检查越界，测试越过两个就会报错，不理解，还是用at好些

 

标签：do,int,Quicksort,while,算法,vector,Quicksort1
来源： https://www.cnblogs.com/jiafushunaixiaomeng/p/16434105.html