双向链表排序，大神看看为啥数据老是丢失

Question

上代码

 #include <iostream>
#include<time.h>
#include<stdlib.h>
using namespace std;

typedef struct node
{
    int date;
    struct node *next;
    struct node *prior;
}node;

class Link
{
private:
    node *first;
    node *last;
    node *temp;
    int len;
public:
    void addLink();
    void showLink();
    void Swap(node *,node *);
    void sort();
    int getLen() const {
        return len;
    }

    void setLen(int len) {
        this->len = len;
    }

};

void Link::addLink()
{
    srand((unsigned)time(NULL));
    for(int i=1;i<=len;i++)
    {
        if(i==1)
        {
            node *newnode=new node;
            newnode->date=rand()%101;
            first=newnode;
            temp=newnode;
            first->prior=NULL;

        }else if(i==len){
            node *newnode=new node;
            newnode->date=rand()%101;
            last=newnode;
            temp->next=last;
            last->prior=temp;
            temp=newnode;
            temp->next=NULL;

        }else
        {
            node *newnode=new node;
            newnode->date=rand()%101;
            temp->next=newnode;
            newnode->prior=temp;
            temp=newnode;
        }
    }


}

void Link::showLink()
{
    node *temp=new node;
    temp=first;
    while(temp!=NULL)
    {
        cout<<temp->date<<"  ";
        temp=temp->next;
    }
    cout<<endl;
    temp=last;
    /*while(temp!=NULL)
    {
        cout<<temp->date<<"  ";
        temp=temp->prior;
    }*/

}

上面的是双向链表的建立和打印，代码没错

下面的是选择排序算法，应该也没错

 void Link::sort()
{
    node *i,*j,*k;
    //if(!first->next)
    //return;

    for(i=first;i->next!=NULL;i=k->next)
    {
        for(j=i->next,k=i;j!=NULL;j=j->next)
            if(k->date>j->date)
                k=j;
        if(k!=i)
            Swap(i,k);
    }

下面的是交换链表位置的代码，复制的某位大神（原谅我忘记了他的名字）的代码，由于他的代码中没有对头结点的换位方法，我就自己写了加上去，结果每次运行都会丢失比头结点小的数据

 void Link::Swap(node *p,node *t)
{
    node *temp;
    if(t->next==NULL&&p->prior!=NULL) //t结点是否为尾结点
    {
        if(p->next==t) //p,t结点是否相邻
        {
            //与尾结点相邻的交换代
            t->next=p;
            t->prior=p->prior;
            p->next=NULL;
            p->prior->next=t;
           p->prior=t;
        }
       else
        {
            //与尾结点不相邻的交换代
            t->next=p->next;
            t->prior->next=p;
            temp=t->prior;
            t->prior=p->prior;
            p->next->prior=t;
            p->next=NULL;
            p->prior->next=t;
            p->prior=temp;
        }
    }
    else if(p->prior==NULL&&t->next!=NULL)
    {
        if(p->next==t)
        {
            p->next=t->next;
            p->next->prior=p;
            p->prior=t;
            t->next=p;
            t->prior=NULL;
        }
        else
        {
            temp=p->next;
            p->next=t->next;
            t->next->prior=p;
            p->prior=t->prior;
            t->prior->next=p;
            t->next=temp;
            temp->prior=t;
            t->prior=NULL;
        }
    }
    else if(p->prior==NULL&&t->next==NULL)
    {
        p->next->prior=t;
        t->next=p->next;
        p->next=NULL;
        t->prior->next=p;
        p->prior=t->prior;
        t->prior=NULL;
    }
    else{
        if(p->next==t) //p,t结点是否相邻
        {
            //相邻的交换代
            t->next->prior=p;
            temp=t->next;
            t->next=p;
            t->prior=p->prior;
            p->next=temp;
            p->prior->next=t;
            p->prior=t;
        }
        else
        {
            //不相邻的交换代
            t->next->prior=p;
            temp=t->next;
            t->next=p->next;
            p->next->prior=t;
            p->next=temp;
            t->prior->next=p;
            temp=t->prior;
            t->prior=p->prior;
            p->prior->next=t;
            p->prior=temp;
       }
    }


}

大神们来帮个忙吧，找错误找的眼睛都出血丝了。。。

Answer 1

http://blog.csdn.net/iluckyning/article/details/8482692