數據結構--二叉樹 的先序，中序，後序遍歷

原理圖：

源程序代碼：

//PostOrderTraverse.cpp
//This function is to postorder BiTree
# include <malloc.h>
# include <iostream>
# include <conio.h>
# define OK 1
# define ERROR 0

using namespace std;

typedef char TElemType;

typedef struct BiTNode  //define structure BiTree
{  TElemType data;
   struct BiTNode *lchild,*rchild;
}BiTNode, *BiTree;

int CreateBiTree(BiTree &T) //createBiTree() sub-function
{  TElemType ch;
   cout<<"Please input data (/ for NULL node!) : ";
   cin>>ch;
   if(ch=='/')  T=NULL;
   else
   {  if(!(T=(BiTNode *)malloc(sizeof(BiTNode))))
      {  cout<<"Overflow!"; //no alloction
  return (ERROR);
      }
      T->data=ch;
      CreateBiTree(T->lchild); //create lchild
      CreateBiTree(T->rchild);  //create rchild
   }
   return (OK);
} //CreateBiTree() end

int PostOrderTraverse(BiTree T) //PostOrderTraverse() sub-function
{
   if(T)
   {  if (PostOrderTraverse(T->lchild))  //traverse lchild
     if(PostOrderTraverse(T->rchild)) //traverse rchild
     {    cout<<T->data<<"->";  //visite T
       return (OK);
        }
 return (ERROR);
   }
   else
      return (OK);
} //PostOrderTraverse() end
int   CentralOrderTraverse(BiTree  T)
{
  if(T)
     {  if (CentralOrderTraverse(T->lchild))  //traverse lchild
     {  cout<<T->data<<"->";  //visite T
       if(CentralOrderTraverse(T->rchild)) //traverse rchild
          return (OK);
     }
      return (ERROR);
     } //if end
   else
      return (OK);
}
int  preOrderTraverse(BiTree T)
{
  if(T)
   {    cout<<T->data<<"->";  //visite T
       if (PostOrderTraverse(T->lchild))  //traverse lchild
     if(PostOrderTraverse(T->rchild))
        return OK; //traverse rchild
      return (ERROR);
   }
   else
      return (OK);
}
int main()   //main() function
{  BiTree T;
   cout<<endl<<endl<<"PostOrderTraverse.cpp";
   cout<<endl<<"=========================";
   cout<<endl<<endl<<"Please input data to create BiTree:"<<endl;
   CreateBiTree(T);  //call CreateBiTree
   std::cout<<"先序遍歷:"<<endl;
   PostOrderTraverse(T);
   std::cout<<"中序遍歷:"<<endl;
   CentralOrderTraverse(T);
   std::cout<<"後序遍歷:"<<endl;
   preOrderTraverse(T);
   cout<<"End !"<<endl<<endl<<"...OK!...";
   getch();
   return 0;
} //main()