单链表快速排序

详细解释在代码中，主要思路是将链表分为三个部分，小于key的链表，等于key的链表，大于key的链表

#include <iostream>
#include<string>
#include <vector>
#include <algorithm>
using namespace std;

class node
{
public:
    int value;
    node *next;
    node():value(0),next(NULL)
    {
    }
    node(int val):value(val),next(NULL)
     {
     }
};

void LinkQuickSort(node*&head)
{
    if (NULL == head->next )
    {
        return;
    }
    const int key = head->value;
    //将链表拆分为三部分
    node *left = new node;//小于key的链表伪头结点
    node *right = new node;//大于key的链表伪头结点
    node *middle = head;//等于key的链表头结点

    node *lastLeft,*lastRight,*temp,*lastMiddle;
    lastRight = right;//记录链表最后一个节点
    lastLeft = left;
    lastMiddle = middle;    
    
    temp=head->next;//从第二个元素开始
    lastMiddle->next = NULL;
    while(NULL != temp)
    {
        if((temp->value)> key)
        {
            lastRight->next = temp;
            lastRight = lastRight->next;
            temp = temp->next;
            lastRight->next=NULL;
        }
        else if ((temp->value) < key)
        {
            lastLeft->next = temp;
            lastLeft = lastLeft->next;
            temp = temp->next;
            lastLeft->next=NULL;
        }
        else
        {
            lastMiddle->next = temp;
            lastMiddle = lastMiddle->next;
            temp = temp->next;
            lastMiddle->next=NULL;
        }
    }
    temp = left;
    left = left->next;
    temp->next = NULL;
    delete temp;//删除伪头结点

    temp = right;
    right = right->next;
    temp->next = NULL;
    delete temp;

    if(NULL != left)
        LinkQuickSort(left);
    if (NULL != right)
        LinkQuickSort(right);

    //合并三个链表
    
    if (NULL != left)//做链表不为空
    {
        temp = left;
        head = left;
        while(temp->next!=NULL)//定位最后一个节点
        {
            temp = temp->next;
        }
        temp->next = middle;
    }
    else
    {
        head = middle;
    }

    lastMiddle->next = right;//right 为NULL也无所谓
    
}

int main()
{
    node *head=new node;

    node *temp = head;
    temp->next = new node(5);
    temp = temp->next;
    temp->next = new node(19);
    temp = temp->next;

    temp->next = new node(19);
    temp = temp->next;

    temp->next = new node(22);
    temp = temp->next;

    temp->next = new node(44);
    temp = temp->next;

    temp = head;
    head = head->next;
    temp->next = NULL;
    delete temp;

    LinkQuickSort(head);

    temp = head;
    while(temp!=NULL)
    {
        cout << temp->value <<" ";
        temp = temp->next;
    }
    cout << endl;

    return 0;
}