链式二叉树的实现



#include <iostream>
#include <string>
#include <stdio.h>
#include <malloc.h>

using namespace std;

struct BTNode
{
 char data;
 struct BTNode * pLchild;//p是指针 L是左  child是孩子
 struct BTNode * pRchild;

};

struct BTNode * CreateBTree()
{
 struct BTNode * pA = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pB= (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pC = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pD = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pE = (struct BTNode *)malloc(sizeof(struct BTNode));

 pA->data = 'A';
 pB->data = 'B';
 pC->data = 'C';
 pD->data = 'D';
 pE->data = 'E';

 pA->pLchild = pB;
 pA->pRchild = pC;
 pB->pLchild = pB->pRchild = NULL;
 pC->pLchild = pD;
 pC->pRchild = NULL;
 pD->pLchild = NULL;
 pD->pRchild = pE;
 pE->pLchild = pE->pRchild = NULL;

 return pA;
}

void PreTraverseBTree(struct BTNode * pT)
{
 /*伪算法
 先访问根节点
  再访问左子树
  再访问右子数*/
 if (NULL != pT )
 {
  cout << pT->data;
 
  if (NULL != pT->pLchild)
   PreTraverseBTree(pT->pLchild);

  if (NULL != pT->pRchild)
  PreTraverseBTree(pT->pRchild);
 } 
}

void InTraverseBTree(struct BTNode * pT)
{
  if (NULL != pT)
  {
   if (NULL != pT->pLchild)
    InTraverseBTree(pT->pLchild);

   cout << pT->data;

   if (NULL != pT->pRchild)
    InTraverseBTree(pT->pRchild);
 }
}

void PostTraverseBTree(struct BTNode * pT)
{
 if (NULL != pT)
 {
  if (NULL != pT->pLchild)
   PostTraverseBTree(pT->pLchild);

  if (NULL != pT->pRchild)
   PostTraverseBTree(pT->pRchild);

  cout << pT->data;
 }
}
int main()
{
 struct BTNode * pT = CreateBTree();
 cout << "先序遍历：";
 PreTraverseBTree(pT);
 cout << endl;
 cout << "中序遍历：";
 InTraverseBTree(pT);
 cout << endl;
 cout << "后序遍历：";
 PostTraverseBTree(pT);
 system("pause");
 return 0;
}