双向链表

原创

油菜花11 2022-11-07 19:10:07 博主文章分类：数据结构与算法 ©著作权

文章标签 链表 #include 结点 文章分类 数据结构与算法人工智能

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意义:

如果算法中需要大量地找某指定结点的前趋结点，使用单链表无疑是灾难性的，因为单链表更适合 "从前往后" 找，而 "从后往前" 找并不是它的强项，在这个情况下使用双向链表

在双向链表中注意指针节点的移动，难度不大

TowWayLink.h

#pragma once
#include <stdlib.h>
#include <string.h>
#include <iostream>

// 玩家信息结构体
typedef struct PlayerInfo
{
  char chName[20]; // 名字
  int iRank; // 排名

  PlayerInfo * pPrior;
  PlayerInfo *pNext;

}STPlayerInfo;

class TowWayLink
{
public:
  TowWayLink();
  ~TowWayLink();

  // 初始化链表
  STPlayerInfo*  InitLink(STPlayerInfo* pLink);

  // 创建节点
  STPlayerInfo* CreateNode(STPlayerInfo& stPlayerInfo);

  // 插入节点
  void InsertNode(STPlayerInfo* pLink,int iPos, STPlayerInfo& stPlayerInfo);

  // 后插法
  void InsertAfter(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo);

  // 删除指定元素
  void DelNode(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo);

  // 改变指定位置的指定元素
  bool ChangeNode(STPlayerInfo* pLink,int iPos, STPlayerInfo& stPlayerInfo);

  // 查询指定元素的位置
  STPlayerInfo * QueryNodeByNo(STPlayerInfo* pLink, int iPos,STPlayerInfo& stPlayerInfo);

  // 查询指定元素的节点地址
  STPlayerInfo * QueryNodePos(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo);

  // 输出、打印链表
  void PrintLink(STPlayerInfo* pLink);

  // 逆序打印
  void PrintLinkReverseOrder(STPlayerInfo* plink);

  // 测试方法
  void TestLink();
private:

};

TowWayLink.cpp

#include "TowWayLink.h"

TowWayLink::TowWayLink()
{
}

TowWayLink::~TowWayLink()
{
}

// 初始化链表
STPlayerInfo*  TowWayLink::InitLink(STPlayerInfo* pLink)
{
  pLink = (STPlayerInfo*)malloc(sizeof(STPlayerInfo));
  strcpy(pLink->chName, "#");

  pLink->pPrior = NULL;
  pLink->pNext = NULL;

  return pLink;
}

// 双向链表
STPlayerInfo* TowWayLink::CreateNode(STPlayerInfo& stPlayerInfo)
{
  STPlayerInfo *pNode = (STPlayerInfo*)malloc(sizeof(STPlayerInfo));

  pNode->pPrior = NULL;
  pNode->pNext = NULL;

  strcpy(pNode->chName,stPlayerInfo.chName);
  pNode->iRank = stPlayerInfo.iRank;

  return pNode;
}

// 插入链表
void TowWayLink::InsertNode(STPlayerInfo* pLink, int iPos, STPlayerInfo& stPlayerInfo)
{
  STPlayerInfo *pNode = CreateNode(stPlayerInfo); // 新节点

  if(1 == iPos) // 首元节点特殊考虑
  {
    pNode->pNext = pLink->pNext; // 新节点尾结点处理
    pNode->pPrior = pLink; // 新节点的头结点处理

    pLink->pNext = pNode; // 新节点前节点处理
    pLink->pNext->pPrior = pNode; // 新节点后节点处理
    return;
  }

  // 找到指定位置的节点
  for(int i = 1; i < iPos; i++)
  {
    if(NULL == pLink->pNext)
    {
      return;
    }

    pLink = pLink->pNext;
  }

  pNode->pNext = pLink->pNext; // 新节点尾结点处理
  pNode->pPrior = pLink; // 新节点的头结点处理

  pLink->pNext = pNode; // 新节点前节点处理
  pLink->pNext->pPrior = pNode; // 新节点后节点处理
}

// 后插法
void TowWayLink::InsertAfter(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo)
{
  STPlayerInfo *pNode = CreateNode(stPlayerInfo); // 新节点

  // 寻找尾结点
  while(pLink->pNext)
  {
    pLink = pLink->pNext;
  }

  pLink->pNext = pNode;
  pNode->pPrior = pLink;
}

// 删除指定元素
void TowWayLink::DelNode(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo)
{
  if(NULL == pLink)
  {
    return;
  }

  // 目标字符
  char chName[20];
  strcpy(chName, stPlayerInfo.chName);

  pLink = pLink->pNext;

  while(pLink)
  {
    if(0 == strcmp(chName, pLink->chName))
    {
      break;
    }
    pLink = pLink->pNext;
  }

  STPlayerInfo* pPreNode = pLink->pPrior;
  pPreNode->pNext = pLink->pNext;

  free(pLink);
  pLink = NULL;
}

// 修改节点
bool TowWayLink::ChangeNode(STPlayerInfo* pLink, int iPos, STPlayerInfo& stPlayerInfo)
{
  if( (iPos <=0)
    || (NULL == pLink))
  {
    return false;
  }

  STPlayerInfo* pLinkCurr = QueryNodeByNo(pLink,iPos,stPlayerInfo);

  strcpy(pLinkCurr->chName, stPlayerInfo.chName);
  pLinkCurr->iRank = stPlayerInfo.iRank;

  return true;
}

// 查询节点
STPlayerInfo * TowWayLink::QueryNodeByNo(STPlayerInfo* pLink, int iPos, STPlayerInfo& stPlayerInfo)
{
  if( (NULL == pLink)
    ||(iPos <=0) )
  {
    return NULL;
  }
  int iCount = 0;
  while(pLink->pNext)
  {
    iCount++;
    pLink = pLink->pNext;
    if(iCount == iPos)
    {
      return pLink;
    }
  }
  return NULL;
}

// 查询指定节点地址
STPlayerInfo * TowWayLink::QueryNodePos(STPlayerInfo* pLink, STPlayerInfo& stPlayerInfo)
{
  if(!pLink)
  {
    return NULL;
  }
  while(pLink->pNext)
  {
    pLink = pLink->pNext;
    if(0 == strcmp(pLink->chName,stPlayerInfo.chName))
    {
      return pLink;
    }
  }
  return NULL;
}

// 输出链表
void TowWayLink::PrintLink(STPlayerInfo* pLink)
{
  pLink = pLink->pNext;
  while(pLink)
  {
    char chName[20];
    int iRank;
    strcpy(chName,pLink->chName);
    iRank = pLink->iRank;

    std::cout <<"Name " << chName<<"  Rank "<<iRank<< std::endl;
    pLink = pLink->pNext;
  }
}

// 逆序输出链表
void TowWayLink::PrintLinkReverseOrder(STPlayerInfo* plink)
{
  if(NULL == plink)
  {
    return;
  }
  STPlayerInfo* pEndNode = NULL;
  while(plink->pNext)
  {
    plink = plink->pNext;
  }
  pEndNode = plink; // 尾节点
  while(pEndNode->pPrior)
  {
    if(0 == strcmp("#", pEndNode->chName))
    {
      return;
    }

    std::cout << "Name "<< pEndNode->chName <<"Rank "<< pEndNode->iRank << std::endl;
    pEndNode = pEndNode->pPrior;
  }
}

// 测试方法
void TowWayLink::TestLink()
{
  STPlayerInfo* pHead= NULL;
  STPlayerInfo* pLink = InitLink(pHead); // 初始化链表，活得链表头

  STPlayerInfo stApple;
  strcpy(stApple.chName,"Apple");
  stApple.iRank = 1;
  InsertAfter(pLink,stApple);

  STPlayerInfo stBanana;
  strcpy(stBanana.chName, "Banana");
  stBanana.iRank = 2;
  InsertAfter(pLink, stBanana);

  STPlayerInfo stMelon;
  strcpy(stMelon.chName, "Melon");
  stMelon.iRank = 3;
  InsertAfter(pLink, stMelon);

  STPlayerInfo stCoco;
  strcpy(stCoco.chName, "Coco");
  stCoco.iRank = 4;
  InsertAfter(pLink, stCoco);

  //PrintLink(pLink);
  
  // 删除指定元素
  //std::cout <<"删除指定元素" << std::endl;
  //DelNode(pLink, stMelon);
  //PrintLink(pLink);
  /*
  STPlayerInfo stOrange;
  strcpy(stOrange.chName, "Orange");
  stOrange.iRank = 21;
  InsertNode(pLink, 1, stOrange);

  STPlayerInfo stLemon;
  strcpy(stLemon.chName, "Lemon");
  stLemon.iRank = 23;
  InsertNode(pLink, 3, stLemon);
  */
  // 添加指定地点的元素
  //std::cout << "添加之后" << std::endl;
  //PrintLink(pLink);

  // 修改节点
//  STPlayerInfo stCoconut;
//  strcpy(stCoconut.chName, "Coconut");
//  stCoconut.iRank = 5;
//  InsertNode(pLink, 5, stCoconut);
//  ChangeNode(pLink,3, stCoconut);
//  PrintLink(pLink);
  PrintLinkReverseOrder(pLink);
  
}

main.cpp

#include <iostream>
#include "TowWayLink.h"
using namespace std;

int main()
{
  TowWayLink mTowWayLink;

  mTowWayLink.TestLink();

  cin.get();
  return 0;
}