快速排序

最新推荐文章于 2024-07-17 10:35:12 发布

原创最新推荐文章于 2024-07-17 10:35:12 发布 · 961 阅读

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本文介绍了一种快速排序算法的具体实现过程，并提供了两个不同版本的快速排序函数。通过递归方式将数组分为较小元素和较大元素两部分，最终实现整个数组的排序。文中还展示了排序前后数组的变化情况。

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#include<iostream>
#include <stdio.h>
using namespace std;
void QuickSort(int *a,int left,int right)
{
if ( left < right )
{
int i = left,t;
int j = right + 1;
int pivot = a[left];
do
{
   do
   {
    i++;
   } while ( a[i] < pivot );
   do
   {
    j--;
   } while ( a[j] > pivot );
   if ( i < j )
   {
    t=a[i];a[i]=a[j];a[j]=t;
   }
} while ( i < j );
if (left != j)
{
   t=a[left];a[left]=a[j];a[j]=t;
}

QuickSort(a,left,j-1);
QuickSort(a,j+1,right);
}
}
void print(const int *const pHead,int max)
{
    cout<<"============================="<<endl;
    for(int i = 0; i < max; ++i)
    {
        cout<<pHead[i]<<" ";
    }
    cout<<endl<<"============================"<<endl;
}

void quickSort1(int *const pHead, int begin, int end)
{
    printf("begin is %d end is %d\r\n",begin,end);
    if(begin < end)
    {
        int i = begin + 1, j = end, temp;
        int key = pHead[begin];
        //while(i<j)
/*
do while will exec noce at least
but while may won't exec!!
*/
        while(i <= j)//Note:when it has two we have to compare once
        {
            while(pHead[i] < key)
            {
                i++;
            }
            while(pHead[j] > key)
            {
                j--;
            }
            if(i < j)
            {
                temp = pHead[i];
                pHead[i] = pHead[j];
                pHead[j] = temp;
            }
        }
        if(begin != j)
        {
            temp = pHead[begin];
            pHead[begin] = pHead[j];
            pHead[j] = temp;
        }
        print(pHead, 7);
        quickSort1(pHead, begin, j - 1);
        quickSort1(pHead, j + 1, end);
    }
}
int main(void)
{
    int array[7] = {5,6,1,4,8,7,2};
    cout<<"===========before quick sort =========="<<endl;
    print(array,7);
// QuickSort(array,0,6);
    quickSort1(array,0,6);
    cout<<"===========after quick sort============"<<endl;
    print(array,7);
    return 0;
}