chlclan

树的遍历：实际访问树中各个节点时，需要路过节点三次，如果如果第一次访问该节点就对其实施Visit函数的话，称为先序遍历，第二访问时实施Visit函数，则为中序遍历，最后访问时实施则为后序遍历。



#include <stdio.h>
#include <stdlib.h>

typedef int    TElemType;
//typedef 1 OK;
//typedef 0 ERROR;

#define OK 1;
#define ERROR 0;

typedef struct BiTNode {
 TElemType data;
 struct BiTNode  *lchild, *rchild;
}BiTNode;

int PrintElem(TElemType e){
 printf("Node Elem is %d", e);
 return OK; 
}

int PreOderTraverse(BiTNode *tree, int(* PrintElem)(TElemType e)){
 if(tree){
  if(PrintElem(tree->data))
   if(PreOderTraverse(tree->lchild, PrintElem))
    if(PreOderTraverse(tree->rchild,PrintElem))
     return OK;
  return ERROR;
       
 }
 else
  return OK;
}

//Create New Tree;

int CreateBiTree(BiTNode *tree){
 BiTNode *T;
 printf("please input int data to create bitree, enter 0 for finishing\n");
 TElemType i;
 scanf("%d",&i);
 if (i == 0){
  T = NULL;
  printf("Tree is NULL \n ");
  return ERROR;
 }
 else {
  if(!(T = (BiTNode *)malloc(sizeof(BiTNode)))){
   printf("OverFlow\n");
   return ERROR;
  }
  T->data = i;
  CreateBiTree(T->lchild);
  CreateBiTree(T->rchild);
  
 }//else end
}

void main()
{ 
 BiTNode *Tree;
 printf("input data to create a new BiTree \n");
 CreateBiTree(Tree);
 PreOderTraverse(Tree,PrintElem);
 return ;
}