目录
1.带头双向循环链表
2.链表实现
2.1可完成带头双向可循环链表节点的结构体
2.2申请一个可双向循环的节点
2.3初始化链表
2.4尾插
2.5尾删
2.6头插
2.7头删
2.8打印
2.9查找（修改）
2.10在pos之前插入x
2.11删除pos位置
2.12判空
2.13记录链表大小
2.14销毁
3.完整的带头双向循环链表代码
3.1——List.h
3.2——List.c
1.带头双向循环链表
对比：
我们实际中最常用还是 两种 链表结构：1.无头单向非循环链表
用处：
结构简单 ，一般不会单独用来存数据。实际中更多是作为 其他数据结 构的子结构 ，如哈希桶、图的邻接表等等。另外这种结构在 笔试面试 中出现很多。2.带头双向循环链表
用处：
结构在链表中最复杂 ，一般用在单独存储数据。实际中使用的链表数据结构，都是带头双向循环链表。另外这个结构虽然结构复杂，但是使用代码实现以后会发现结构会带来很多优势，反而使得实现功能更简单了。
2.链表实现
2.1可完成带头双向可循环链表节点的结构体
typedef int LTDataType;
typedef struct ListNode
{
struct ListNode* next;
struct ListNode* prev;
LTDataType data;
}LTNode;2.2申请一个可双向循环的节点
LTNode* BuyListNode(LTDataType x)
{
LTNode* node = (LTNode*)malloc(sizeof(LTNode));
if (node == NULL)
{
perror("malloc fail");
exit(-1);
}
node->data = x;
node->next = NULL;
node->prev = NULL;
return node;
}2.3初始化链表
LTNode* ListInit()
{
LTNode* phead = BuyListNode(-1);
phead->next = phead;
phead->prev = phead;
return phead;
}2.4尾插
void LTPushBack(LTNode* phead, LTDataType x)
{
assert(phead);
//方法1
/*LTNode* newnode = BuyListNode(x);
LTNode* tail = phead->prev;
tail->next = newnode;
newnode->prev = tail;
newnode->next = phead;
phead->prev = newnode;*/
//方法2
LTInsert(phead, x);
}2.5尾删
void LTPopBack(LTNode* phead)
{
assert(phead);
assert(phead->next != phead); // 空
//方法1
//LTNode* tail = phead->prev;
//LTNode* tailPrev = tail->prev;
//tailPrev->next = phead;
//phead->prev = tailPrev;
//free(tail);
//方法2
LTErase(phead->prev);
}2.6头插
void LTPushFront(LTNode* phead, LTDataType x)
{
assert(phead);
//方法1（有关顺序）
/*LTNode* newnode = BuyListNode(x);
newnode->next = phead->next;
phead->next->prev = newnode;
phead->next = newnode;
newnode->prev = phead;*/
//方法2（无关顺序）
//LTNode* newnode = BuyListNode(x);
//LTNode* first = phead->next;
phead newnode first
顺序无关
//phead->next = newnode;
//newnode->prev = phead;
//newnode->next = first;
//first->prev = newnode;
//方法3
LTInsert(phead->next, x);
}2.7头删
void LTPopFront(LTNode* phead)
{
assert(phead);
assert(phead->next != phead); // 空
//方法1
/*LTNode* first = phead->next;
LTNode* second = first->next;
free(first);
phead->next = second;
second->prev = phead;*/
//方法2
LTErase(phead->next);
}2.8打印
void LTPrint(LTNode* phead)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
printf("%d ", cur->data);
cur = cur->next;
}
printf("\n");
}2.9查找（修改）
LTNode* LTFind(LTNode* phead, LTDataType x)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
if (cur->data == x)
{
return cur;
}
cur = cur->next;
}
return NULL;
}2.10在pos之前插入x
// 在pos之前插入x
void LTInsert(LTNode* pos, LTDataType x)
{
assert(pos);
LTNode* prev = pos->prev;
LTNode* newnode = BuyListNode(x);
// prev newnode pos
prev->next = newnode;
newnode->prev = prev;
newnode->next = pos;
pos->prev = newnode;
}2.11删除pos位置
// 删除pos位置
void LTErase(LTNode* pos)
{
assert(pos);
LTNode* prev = pos->prev;
LTNode* next = pos->next;
free(pos);
prev->next = next;
next->prev = prev;
}
2.12判空
bool LTEmpty(LTNode* phead)
{
assert(phead);
/*if (phead->next == phead)
{
return true;
}
else
{
return false;
}*/
return phead->next == phead;
}2.13记录链表大小
size_t LTSize(LTNode* phead)
{
assert(phead);
size_t size = 0;
LTNode* cur = phead->next;
while (cur != phead)
{
++size;
cur = cur->next;
}
return size;
}2.14销毁
void LTDestroy(LTNode* phead)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
LTNode* next = cur->next;
free(cur);
cur = next;
}
free(phead);
//phead = NULL;
}3.完整的带头双向循环链表代码
3.1——List.h
#pragma once
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <stdbool.h>
//typedef char LTDataType;
//typedef double LTDataType;
typedef int LTDataType;
typedef struct ListNode
{
struct ListNode* next;
struct ListNode* prev;
LTDataType data;
}LTNode;
//创建节点
LTNode* BuyListNode(LTDataType x);
//初始化
LTNode* LTInit();
//打印
void LTPrint(LTNode* phead);
//尾插尾删
void LTPushBack(LTNode* phead, LTDataType x);
void LTPopBack(LTNode* phead);
//头插头删
void LTPushFront(LTNode* phead, LTDataType x);
void LTPopFront(LTNode* phead);
//查找
LTNode* LTFind(LTNode* phead, LTDataType x);
// pos前面插入
void LTInsert(LTNode* pos, LTDataType x);
// pos位置删除
void LTErase(LTNode* pos);
//判空
bool LTEmpty(LTNode* phead);
//大小
size_t LTSize(LTNode* phead);
//销毁
void LTDestroy(LTNode* phead);3.2——List.c
#include "List.h"
LTNode* BuyListNode(LTDataType x)
{
LTNode* node = (LTNode*)malloc(sizeof(LTNode));
if (node == NULL)
{
perror("malloc fail");
exit(-1);
}
node->data = x;
node->next = NULL;
node->prev = NULL;
return node;
}
LTNode* LTInit()
{
LTNode* phead = BuyListNode(-1);
phead->next = phead;
phead->prev = phead;
return phead;
}
void LTPrint(LTNode* phead)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
printf("%d ", cur->data);
cur = cur->next;
}
printf("\n");
}
void LTPushBack(LTNode* phead, LTDataType x)
{
assert(phead);
//方法1
/*LTNode* newnode = BuyListNode(x);
LTNode* tail = phead->prev;
tail->next = newnode;
newnode->prev = tail;
newnode->next = phead;
phead->prev = newnode;*/
//方法2
LTInsert(phead, x);
}
void LTPopBack(LTNode* phead)
{
assert(phead);
assert(phead->next != phead); // 空
//方法1
//LTNode* tail = phead->prev;
//LTNode* tailPrev = tail->prev;
//tailPrev->next = phead;
//phead->prev = tailPrev;
//free(tail);
//方法2
LTErase(phead->prev);
}
void LTPushFront(LTNode* phead, LTDataType x)
{
assert(phead);
//方法1（有关顺序）
/*LTNode* newnode = BuyListNode(x);
newnode->next = phead->next;
phead->next->prev = newnode;
phead->next = newnode;
newnode->prev = phead;*/
//方法2（无关顺序）
//LTNode* newnode = BuyListNode(x);
//LTNode* first = phead->next;
phead newnode first
顺序无关
//phead->next = newnode;
//newnode->prev = phead;
//newnode->next = first;
//first->prev = newnode;
//方法3
LTInsert(phead->next, x);
}
void LTPopFront(LTNode* phead)
{
assert(phead);
assert(phead->next != phead); // 空
//方法1
/*LTNode* first = phead->next;
LTNode* second = first->next;
free(first);
phead->next = second;
second->prev = phead;*/
//方法2
LTErase(phead->next);
}
LTNode* LTFind(LTNode* phead, LTDataType x)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
if (cur->data == x)
{
return cur;
}
cur = cur->next;
}
return NULL;
}
// 在pos之前插入x
void LTInsert(LTNode* pos, LTDataType x)
{
assert(pos);
LTNode* prev = pos->prev;
LTNode* newnode = BuyListNode(x);
// prev newnode pos
prev->next = newnode;
newnode->prev = prev;
newnode->next = pos;
pos->prev = newnode;
}
// 删除pos位置
void LTErase(LTNode* pos)
{
assert(pos);
LTNode* prev = pos->prev;
LTNode* next = pos->next;
free(pos);
prev->next = next;
next->prev = prev;
}
//判空
bool LTEmpty(LTNode* phead)
{
assert(phead);
/*if (phead->next == phead)
{
return true;
}
else
{
return false;
}*/
return phead->next == phead;
}
size_t LTSize(LTNode* phead)
{
assert(phead);
size_t size = 0;
LTNode* cur = phead->next;
while (cur != phead)
{
++size;
cur = cur->next;
}
return size;
}
void LTDestroy(LTNode* phead)
{
assert(phead);
LTNode* cur = phead->next;
while (cur != phead)
{
LTNode* next = cur->next;
free(cur);
cur = next;
}
free(phead);
//phead = NULL;
}
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