4-11 先序输出叶结点 (15分)
本题要求按照先序遍历的顺序输出给定二叉树的叶结点。
函数PreorderPrintLeaves应按照先序遍历的顺序输出给定二叉树BT的叶结点，格式为一个空格跟着一个字符。
裁判测试程序样例：
#include <stdio.h>
#include <stdlib.h>
typedef char ElementType;
typedef struct TNode *Position;
typedef Position BinTree;
struct TNode{
ElementType Data;
BinTree Left;
BinTree Right;
};
BinTree CreatBinTree(); /* 实现细节忽略 */
void PreorderPrintLeaves( BinTree BT );
int main()
{
BinTree BT = CreatBinTree();
printf("Leaf nodes are:");
PreorderPrintLeaves(BT);
printf("
");
return 0;
}
/* 你的代码将被嵌在这里 */
输出样例（对于图中给出的树）：
Leaf nodes are: D E H I
1 // 4-11 先序输出叶结点 2 // 3 // Created by Haoyu Guo on 05/02/2017. 4 // Copyright © 2017 Haoyu Guo. All rights reserved. 5 // 6 #include <stdio.h> 7 #include<iostream> 8 #include <stdlib.h> 9 using namespace std; 10 #define OVERFLOW -2 11 typedef char ElementType; 12 typedef struct TNode *Position; 13 typedef Position BinTree; 14 struct TNode{ 15 ElementType Data; 16 BinTree Left; 17 BinTree Right; 18 }; 19 int CreatBinTree(BinTree &T)//创建二叉树 20 { 21 char ch;//按先序的方式输入 22 cin >> ch;//递归中自然带着一些重复，就不需要循环了 23 if (ch == '#') T=NULL; 24 else { 25 if (!(T = (BinTree)malloc(sizeof(TNode)))) exit(OVERFLOW); 26 T->Data = ch; 27 CreatBinTree(T->Left); 28 CreatBinTree(T->Right); 29 } 30 return 0; 31 } 32 33 void PreorderPrintLeaves( BinTree BT ); 34 35 int main() 36 { 37 BinTree BT; 38 CreatBinTree(BT);//创建一个 39 printf("Leaf nodes are:"); 40 PreorderPrintLeaves(BT); 41 printf(" "); 42 return 0; 43 } 44 /* 你的代码将被嵌在这里 */ 45 void PreorderPrintLeaves( BinTree BT)//先序输出 46 { 47 if(BT==NULL) return; 48 else{ 49 if(BT->Left==NULL&&BT->Right==NULL) 50 printf(" %c",BT->Data); 51 PreorderPrintLeaves(BT->Left); 52 PreorderPrintLeaves(BT->Right); 53 } 54 }