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C++从单向链表变为双向链表

转载 作者:行者123 更新时间:2023-11-30 05:42:55 25 4
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我使用单链表编写了这段代码。现在我想把它改成双向链表。我尝试了一些不同的东西,但一切都搞砸了。我的代码中几乎没有无用的行,但它基本上是一个单链表。将其更改为双向链表的正确方法是什么?

#pragma once

#include "Exhibit.h"

struct Node
{
Exhibit exhibit;
Node *next;
};

class Museum
{
private:
Node *p;
Node *d;
Exhibit *Ex;
int n;
int nmax;
public:
Museum();
~Museum();

void Start() { d = p; }
bool HasNext() { if (d == NULL) return false; return true; }
void Next() { d = d->next; }
Exhibit GetExhibit() const { return d->exhibit; }
int GetN() { return n; }

void Sort();
void AddExhibit(Exhibit e);
void RemoveExpensive(int p); //Removes elements more expensive than int p
};

Museum::Museum()
{
p = NULL;
d = NULL;

}

Museum::~Museum()
{
Node * element;
while (p)
{
element = p;
p = p->next;
delete element;
}
p = NULL;
d = NULL;

}

void Museum::AddExhibit(Exhibit e)
{
Node *element = new Node;

element->exhibit = e;
element->next = p;
p = element;
}

int CountExhibits(string CDfv)
{
string line;
int count = 0;
ifstream fd(CDfv.c_str());
while (!fd.eof())
{
getline(fd, line);
count++;
}
fd.close();
return count;
}

void Museum::Sort()
{
// traverse the entire list
for (Node *list = p; list->next != NULL; list = list->next)
{
// compare to the list ahead
for (Node *pass = list->next; pass != NULL; pass = pass->next)
{
// compare and swap
if (list->exhibit.Date() > pass->exhibit.Date())
{
// swap
Exhibit temp = list->exhibit;
list->exhibit = pass->exhibit;
pass->exhibit = temp;
}
}
}
}

void Museum::RemoveExpensive(int pr)
{
Node *pPre = NULL, *pDel = NULL;


pPre = p;
pDel = p->next;

/* traverse the list and check the value of each node */
while (pDel != NULL) {
if (pDel->exhibit.Price() > pr) {
/* Update the list */
pPre->next = pDel->next;
/* If it is the last node, update the tail */
if (pDel == d) {
d = pPre;
}
delete pDel; /* Here only remove the first node with the given value */
pDel = pPre;
/* break and return */
}
pPre = pDel;
pDel = pDel->next;
}


/* Check whether it is the head node?
if it is, delete and update the head node */
if (p->exhibit.Price() > pr) {
/* point to the node to be deleted */
pDel = p;
/* update */
p = pDel->next;
delete pDel;

}
}

编辑:我的新 AddExhibit() 方法:

void Museum::AddExhibit(Exhibit e)
{
Node *element = new Node;

element->exhibit = e;

if (p == NULL)
p = d = element;
else
{
p->prev = element;
element->next = p;
p = element;

}
//element->next = p;
//p = element;
}

最佳答案

我用这个 AddExhibit() 方法解决了我的问题:

void Museum::AddExhibit(Exhibit e)
{
Node *element = new Node;

element->exhibit = e;

element->next = p;
element->prev = NULL;
if (p == NULL)
d = element;
else
p->prev = element;
p = element;
}

我不知道它是否完全正确,但它适合我的情况。

关于C++从单向链表变为双向链表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30447265/

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