【数据结构】- 几个步骤教你认识并实现一个链表之带头(哨兵位)双向循环链表(中)

2023-06-28 43

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简介： 数据结构学习第八弹——链表之带头双向循环链表（中）

🌟一、带头双向循环链表

🌏1.1头删：

💫1.1.1代码：

void LTPopFront(LTNode* phead)
{
  assert(phead);
  LTNode* cur = phead->next;
  phead->next = cur->next ;
  cur->next->prev = phead;
  free(cur);
}

💫1.1.2流程图：

定义一个指针时：(代码如上图)

定义两个指针时：(建议使用两个—代码如下图)

🌏1.2尾删：

💫1.2.1代码：

void LTPopBack(LTNode* phead)
{
  assert(phead);
  assert(!LTEmpty(phead));
  LTNode* tail = phead->prev;
  LTNode* tailPrev = tail->prev;
  free(tail);
  phead->prev = tailPrev;
  tailPrev->next = phead;
}

💫1.2.2流程图：

第一种：

第二种：

第三种：需要注意

🌏1.3查找：

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;
}

🌏1.4在pos位置之前插入：

💫1.4.1代码：

void LTInsert(LTNode* pos, LTDataType x)
{
  assert(pos);
  LTNode* newnode = BuyLTNode(x);
  pos->prev->next  = newnode;
  newnode->prev = pos->prev;
  newnode->next = pos;
  pos->prev = newnode;
  //第二种：
  ///LTNode* prev = pos->prev;
  //prev->next = newnode;
  //newnode->prev = prev;
  //pos->prev = newnode;
  //newnode->next = pos;
}

💫1.4.2流程图：

第一种：

第二种：

🌏1.5在pos位置删除：

💫1.5.1代码：

void LTErase(LTNode* pos)//要注意不能传哨兵位
{
  assert(pos);
  LTNode* posPrev = pos->prev;
  LTNode* posNext = pos->next;
  posPrev->next = posNext;
  posNext->prev = posPrev;
  free(pos);
}

💫1.5.2流程图：

🌏1.6释放链表：

void LTDestroy(LTNode* phead)
{
  assert(phead);
  LTNode* cur = phead->next;
  while (cur != phead)
  {
    LTNode* next = cur->next;
    free(cur);
    cur = next;
  }
  free(phead);
}

🌟二、完整带头双向循环链表

//List.h
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<stdbool.h>
typedef int LTDataType;
typedef struct ListNode
{
  struct ListNode* next;
  struct ListNode* prev;
  LTDataType data;
}LTNode;
LTNode* LTInit();
void LTNodePrint(LTNode* phead);
bool LTEmpty(LTNode* phead);
void LTPushFront(LTNode* phead, LTDataType x);
void LTPushBack(LTNode* phead, LTDataType x);
void LTPopFront(LTNode* phead);
void LTPopBack(LTNode* phead);
LTNode* LTFind(LTNode* phead, LTDataType x);
//在pos之前插入
void LTInsert(LTNode* pos, LTDataType x);
//删除pos位置的值
void LTErase(LTNode* pos);
void LTDestroy(LTNode* phead);
//List.c
#define _CRT_SECURE_NO_WARNINGS 1
#include"List.h"
bool LTEmpty(LTNode* phead)
{
  assert(phead);
  return phead->next == phead;
}
LTNode* BuyLTNode(LTDataType x)
{
  LTNode* newnode = (LTNode*)malloc(sizeof(LTNode));
  if (newnode == NULL)
  {
    perror("malloc fail");
  }
  newnode->data = x;
  newnode->next = NULL;
  newnode->prev = NULL;
  return newnode;
}
LTNode* LTInit()
{
  LTNode* phead = BuyLTNode(-1);
  phead->next = phead;
  phead->prev = phead;
  return phead;
}
void LTNodePrint(LTNode* phead)
{
  assert(phead);
  LTNode* cur = phead->next;
  printf("guard<==>");
  while (cur != phead)
  {
    printf("%d<==>", cur->data);
    cur = cur->next;
  }
  printf("\n");
}
void LTPushFront(LTNode* phead, LTDataType x)
{
  LTNode* newnode = BuyLTNode(x);
  LTNode* cur = phead->next;
  newnode->prev = phead;
  phead->next = newnode;
  newnode->next = cur;
  cur->prev = newnode;
}
void LTPushBack(LTNode* phead, LTDataType x)
{
  assert(phead);
  LTNode* newnode = BuyLTNode(x);
  LTNode* tail = phead->prev;
  tail->next = newnode;
  newnode->prev = tail;
  newnode->next = phead;
  phead->prev = newnode;
}
void LTPopFront(LTNode* phead)
{
  assert(phead);
  LTNode* cur = phead->next;
  //LTNode* next = cur->next;
  phead->next = cur->next ;
  cur->next->prev = phead;
  free(cur);
}
void LTPopBack(LTNode* phead)
{
  assert(phead);
  assert(!LTEmpty(phead));
  LTNode* tail = phead->prev;
  LTNode* tailPrev = tail->prev;
  free(tail);
  phead->prev = tailPrev;
  tailPrev->next = phead;
}
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;
}
void LTInsert(LTNode* pos, LTDataType x)
{
  assert(pos);
  LTNode* newnode = BuyLTNode(x);
  pos->prev->next  = newnode;
  newnode->prev = pos->prev;
  newnode->next = pos;
  pos->prev = newnode;
  //第二种：
  ///LTNode* prev = pos->prev;
  //prev->next = newnode;
  //newnode->prev = prev;
  //pos->prev = newnode;
  //newnode->next = pos;
}
void LTErase(LTNode* pos)//要注意不能传哨兵位
{
  assert(pos);
  LTNode* posPrev = pos->prev;
  LTNode* posNext = pos->next;
  posPrev->next = posNext;
  posNext->prev = posPrev;
  free(pos);
}
void LTDestroy(LTNode* phead)
{
  assert(phead);
  LTNode* cur = phead->next;
  while (cur != phead)
  {
    LTNode* next = cur->next;
    free(cur);
    cur = next;
  }
  free(phead);
}
//Test.c
#define _CRT_SECURE_NO_WARNINGS 1
#include"List.h"
void TestList()
{
  LTNode* plist = LTInit();
  LTPushBack(plist, 1);
  LTPushBack(plist, 2);
  LTPushBack(plist, 3);
  LTPushBack(plist, 4);
  LTNodePrint(plist);
  //LTPushFront(plist, 1);
  //LTPushFront(plist, 2);
  //LTPushFront(plist, 3);
  //LTPushFront(plist, 4);
  //LTNodePrint(plist);
  /*LTPopBack(plist);
  LTNodePrint(plist);*/
  /*LTPopFront(plist);
  LTNodePrint(plist);*/
  /*LTNode* pos = LTFind(plist,3);
  if (pos)
  {
    LTInsert(pos, 30);
  }
  LTNodePrint(plist);*/
  LTNode* pos = LTFind(plist, 2);
  if (pos)
  {
    LTErase(pos, 30);
  }
  LTNodePrint(plist);
  LTDestroy(plist);
  plist = NULL;
}
int main()
{
  TestList();
  return 0;
}

😽总结

😽Ending,今天的链表之带头双向循环链表(中)的内容就到此结束啦~，如果后续想了解更多，就请关注我吧。