二叉树中递归算法的两个应用——数（非）叶子结点的数目和判断是否是排序二叉树

//BinaryTree.h

/* 二叉树的二叉链表结点定义 */
typedef char datatype;
typedef struct BiTNode
{
datatype data;
struct BiTNode * LChild , * RChild ;
} BiTNode , * BiTree ;

//数叶子结点的数目
/*
Author: WadeFelix RenV
*/
#include <stdio.h>
#include <stdlib.h>
#include "BinaryTree.h"
int countLeaf( BiTree BT )
{
if( BT == NULL ) return 0;
if( BT->LChild==NULL && BT->RChild==NULL ) return 1;
return(countLeaf(BT->LChild)+countLeaf(BT->RChild));
}

//数非叶子结点的数目

int countNotLeaf( BiTree BT )
{
if( BT == NULL ) return 0;
if( BT->LChild==NULL && BT->RChild==NULL ) return 0;
return(1+countNotLeaf(BT->LChild)+countNotLeaf(BT->RChild));
}

//判断是否是排序二叉树
#include <stdio.h>
#include <stdlib.h>
#include "BinaryTree.h"
int isPaiXu( BiTree BT )
{
if( BT == NULL )return 1;
if( BT->LChild && (BT->LChild->data > BT->data) )return 0;
if( BT->RChild && (BT->RChild->data < BT->data) )return 0;

return( isPaiXu(BT->LChild)&&isPaiXu(BT->RChild) );
}