二叉树遍历实现c++

输入一棵二元查找树，将该二元查找树转换成一个排序的双向链表。
要求不能创建任何新的结点，只调整指针的指向。
  

 

 

 

转换成双向链表

先序列：H      F       C       D      M     I        N

中序列：C       F       D      H      I        M     N

后序列：C       D      F       I        N      M     H  

 

 

 

 

 

#include <iostream>
using namespace std;
struct BSTreeNode{
 char m_val;
 BSTreeNode *m_pLeft;
 BSTreeNode *m_pRight;
};
BSTreeNode *pHead;//链表显示的头结点
BSTreeNode *pListIndex;//游标指针
void showOrderLiust(BSTreeNode *pCurrent);
void createBSTree(BSTreeNode *&pCurrent,char ch)
{
 if (NULL == pCurrent) {
  pCurrent = new BSTreeNode;
  pCurrent->m_val = ch;
  pCurrent->m_pLeft = NULL;
  pCurrent->m_pRight = NULL;
 }else {
  if (pCurrent->m_val > ch) {
   createBSTree(pCurrent->m_pLeft,ch);
  }else if (pCurrent->m_val < ch) {
   createBSTree(pCurrent->m_pRight,ch);
  }
  else
  {
   return;
  }
 }
}
//遍历二叉树/*先序遍历*/
void PreOrderTraverse(BSTreeNode *pCurrent)
{
 if (NULL == pCurrent) {
  return;
 }
 
 if (NULL!=pCurrent)
 {
  //先遍历根节点
  cout<<pCurrent->m_val<<endl;
  //在遍历左节点
  PreOrderTraverse(pCurrent->m_pLeft);
  //在遍历右节点
  PreOrderTraverse(pCurrent->m_pRight);
 }
 
}
//中序遍历
void InOrderTraverse(BSTreeNode *pCurrent)
{
 if (NULL == pCurrent) {
  return;
 }
 if (NULL != pCurrent->m_pLeft) {
  InOrderTraverse(pCurrent->m_pLeft);
 }
 
 showOrderLiust(pCurrent);
 //在遍历右节点
 if (NULL != pCurrent->m_pRight) {
  InOrderTraverse(pCurrent->m_pRight);
 }
}
//后序遍历
void EndOrderTraverse(BSTreeNode *pCurrent)
{
 if (NULL == pCurrent) {
  return;
 }
 if (NULL != pCurrent->m_pLeft) {
  EndOrderTraverse(pCurrent->m_pLeft);
 }
 cout<<pCurrent->m_val<<endl;
 //在遍历右节点
 if (NULL != pCurrent->m_pRight) {
  EndOrderTraverse(pCurrent->m_pRight);
 }
}
/*该二元查找树转换成一个排序的双向链表。
 要求不能创建任何新的结点，只调整指针的指向*/
void showOrderLiust(BSTreeNode *pCurrent)
{
 pCurrent->m_pLeft = pListIndex;
 if (NULL != pListIndex) {
  pListIndex->m_pRight = pCurrent;
 }else
 {
  pHead = pCurrent;
 }
 pListIndex = pCurrent;
 cout<<pCurrent->m_val<<endl;
}
int main(int argc,char**argv)
{
 BSTreeNode *pRoot = NULL;
 pHead = NULL;
 pListIndex = NULL;
 createBSTree(pRoot,'H'); 
 createBSTree(pRoot,'F');
 createBSTree(pRoot,'C');
 createBSTree(pRoot,'D');
 createBSTree(pRoot,'M');
 createBSTree(pRoot,'I');
 createBSTree(pRoot,'N');
 PreOrderTraverse(pRoot);
 InOrderTraverse(pRoot);
 EndOrderTraverse(pRoot);
 delete pRoot;
 return 0;
}