数据结构基础（带头节点的双向循环链表）

DLinkList.h

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>typedef int ElemType;// SList - 单链表
// DList - 双链表
// 带头节点的双向循环链表 - 最优链表结构，任意位置插入、删除数据，时间复杂度O(1)
typedef struct ListNode{struct ListNode* prev;struct ListNode* next;ElemType data;
}ListNode;// 初始化
ListNode* ListInit();
// 打印
void ListPrint(ListNode* phead);
// 销毁
void ListDestory(ListNode* phead);
// 尾插
void ListPushBack(ListNode* phead, ElemType x);
// 头产
void ListPushFront(ListNode* phead, ElemType x);
// 尾删
void ListPopBack(ListNode* phead);
// 头删
void ListPopFront(ListNode* phead);// 查找节点的pos位置
ListNode* ListFind(ListNode* phead, ElemType x);
// 在pos位置前插入
void ListInsert(ListNode* pos, ElemType x);
// 删除pos位置的值
void ListErase(ListNode* pos);

DLinkList.c

#define _CRT_SECURE_NO_WARNINGS 1#include "DList.h"// 返回节点（头节点、要插入的节点）
ListNode* BuyListNode(ElemType x)
{ListNode* newNode = (ListNode*)malloc(sizeof(ListNode));newNode->data = x;newNode->prev = NULL;newNode->next = NULL;return newNode;
}
// 初始化
ListNode* ListInit()
{ListNode* phead = BuyListNode(0);// 申请头节点,数据域传0phead->next = phead;phead->prev = phead;return phead;
}
// 打印
void ListPrint(ListNode* phead)
{assert(phead);ListNode* cur = phead->next;while (cur != phead){printf("%d ", cur->data);cur = cur->next;}printf("\n");
}
// 销毁
void ListDestory(ListNode* phead)
{assert(phead);ListNode* cur = phead->next;while (cur != phead){ListNode* next = cur->next;// 先找到要删节点的下一个节点free(cur);cur = next;}free(phead);phead = NULL;
}
// 尾插（直接调用Insert（在pos位置前插入））
void ListPushBack(ListNode* phead, ElemType x)
{assert(phead);// 头节点不为空//ListNode* newNode = BuyListNode(x); 带头的双向循环链表不考虑没有节点，有节点的情况//ListNode* tail = phead->prev;// 定义一个尾指针，指向头节点的前驱 画图分析//tail->next = newNode;//newNode->prev = tail;//newNode->next = phead;//phead->prev = newNode;ListInsert(phead, x);}
// 头插（直接调用Insert（在pos位置前插入））
void ListPushFront(ListNode* phead, ElemType x)
{assert(phead); 没有节点也不会有问题//ListNode* first = phead->next;//ListNode* newNode = BuyListNode(x);//phead->next = newNode;//newNode->prev = phead;//newNode->next = first;//first->prev = newNode;ListInsert(phead->next, x);}// 头删（可以调用Erase）
void ListPopFront(ListNode* phead)
{//assert(phead);//assert(phead->next != phead);// 链表没有一个节点//ListNode* first = phead->next;//ListNode* second = first->next;//phead->next = second;//second->prev = phead;//free(first);//first = NULL;ListErase(phead->next);
}
// 尾删（可以调用Erase）
void ListPopBack(ListNode* phead)
{//assert(phead);//assert(phead->next != phead);// 链表没有一个节点//ListNode* tail = phead->prev;//ListNode* prev = tail->prev;//prev->next = phead;//phead->prev = prev;//free(tail);//tail = NULL;ListErase(phead->prev);
}// 查找节点的pos位置
ListNode* ListFind(ListNode* phead, ElemType x)
{assert(phead);ListNode* cur = phead->next;while (cur != phead){if (cur->data == x)return cur;cur = cur->next;}return NULL;
}
// 在pos位置（前！！！）插入
void ListInsert(ListNode* pos, ElemType x)
{assert(pos);ListNode* prev = pos->prev;ListNode* newNode = BuyListNode(x);prev->next = newNode;newNode->prev = prev;newNode->next = pos;pos->prev = newNode;
}
// 删除pos位置的值
void ListErase(ListNode* pos)
{ListNode* prev = pos->prev;ListNode* next = pos->next;prev->next = next;next->prev = prev;free(pos);pos = NULL;}

test.c

#define _CRT_SECURE_NO_WARNINGS 1
#include "DList.h"void testList1()
{ListNode* plist = ListInit();ListPushBack(plist, 1);ListPushBack(plist, 2);ListPushBack(plist, 3);ListPushBack(plist, 4);ListPrint(plist);ListPushFront(plist, 0);ListPushFront(plist, -1);ListPrint(plist);ListPopFront(plist);ListPrint(plist);ListPopBack(plist);ListPrint(plist);ListDestory(plist);
}
void testList2()
{ListNode* plist = ListInit();ListPushBack(plist, 1);ListPushBack(plist, 2);ListPushBack(plist, 3);ListPushBack(plist, 4);ListPrint(plist);ListNode* pos = ListFind(plist, 2);if (pos){pos->data *= 10;printf("找到了，并且乘10\n");}elseprintf("没有找到\n");ListPrint(plist);ListInsert(pos, 300);ListPrint(plist);ListErase(pos);ListPrint(plist);
}
int main()
{testList1();return 0;
}