#pragma once
#include<stdlib.h>
#include<stdio.h>
#include<assert.h>
typedef int DataType;
typedef struct DNode
{
DataType data;
struct DNode *next;
struct DNode *prev;
}DNode;
DNode *CreateDNode(int data)
{
DNode *node = (DNode*)malloc(sizeof(DNode));
node->data = data;
node->prev = node->next = NULL;
return node;
}
void DNodeInit(DNode **ppHead)
{
assert(ppHead != NULL);
DNode *node = CreateDNode(0);
node->next = node;
node->prev = node;
*ppHead = node;
}
void DNodePushFront(DNode *head,DataType data)
{
DNode *node = CreateDNode(0);
node->prev = head;
node->next = head->next;
head->next->prev = node;
head->next = node;
}
void DNodePushBack(DNode *head,DataType data)
{
DNode *node = CreateDNode(0);
node->prev = head->prev;
node->next;
node = head->prev->next;
head->prev = node;
}
void DListInsert(DNode *head, DataType data)
{
DNode *node = CreateDNode(data);
node->prev = head->prev;
node->next = head;
head->prev->next = node;
head->prev = node;
}
void DListPopFront(DNode *head)
{
assert(head->next != head);
DNode *first = head->next;
DNode *second = head->next->next;
head->next = second;
second->prev = head;
head->next = head;
}
void DListPopBack(DNode *head)
{
assert(head->next != head);
DNode *node;
node->prev->next = head;
head->prev = node->prev;
free(node);
}
void DListErase(DNode *head, DNode *pos)
{
assert(head->next != head);
pos->prev->next = pos->next;
pos->next->prev = pos->prev;
free(pos);
}
void DListClear(DNode *head)
{
DNode *next;
for (DNode *cur = head->next; cur != head; cur = next)
{
next = cur->next;
free(cur);
}
head->prev = head->next = head;
}
void DNodePrintf(DNode *head)
{
for (DNode *cur = head->next; cur != head; cur = cur->next)
{
printf("%d", cur->data);
}
printf("\n");
}
void Test()
{
DNode *List;
DNodeInit(&List);
DNodePushBack(List, 1);
DNodePushBack(List, 2);
DNodePushBack(List, 3);
DNodePushBack(List, 4);
DNodePushBack(List, 5);
DNodePrintf(List);
}
双向带头循环链表时间复杂度O（1），因为是循环首位相接，不管是头，尾相加节点都可以直接确定位置，并不需要遍历（除去clear,和打印链表必须要遍历链表）。
我们在增删查改双向带头链表时候，需要注意的是该表head,最后节点
的指向，以及将原有指向关系换成新的指向关系。注意增删改查，对
链表指向关系改变的影响这个是关键，也是需要注意的。**以及我们
需要注意在clear不能删除头节点，在节点修改时候，我们需要保证头
节点安全，不能破环这个，匿名如果简单实现循环带头双链表为题会
简单很多的。