【练习时间】2021/3/28
【题目名称】 交换二叉树的左右子树
输入数据：ABCD###E##F##
输出数据：A F B E C D
【代码分析】

void ExchangeTree(BiNode *bt)
{
	if(bt==NULL)return;
	else{
		BiNode *temp=new BiNode;
		temp=bt->lchild;
		bt->lchild=bt->rchild;
		bt->rchild=temp;
		ExchangeTree(bt->lchild);
		ExchangeTree(bt->rchild);
	}
}

【源代码】

/*
ABCD###E##F##

A B C D E F

A F B E C D
*/
#include <iostream>
using namespace std;
struct BiNode 
{
	char data;
	BiNode *lchild;
	BiNode *rchild;
};
BiNode *CreateTree()
{
	char val;
	cin>>val;
	BiNode *bt=NULL;
	bt=new BiNode;
	if(val=='#')return NULL;
	else{
		bt->data=val;
		bt->lchild=CreateTree();
		bt->rchild=CreateTree();
	}
	
	return bt;
}
void ExchangeTree(BiNode *bt)
{
	if(bt==NULL)return;
	else{
		BiNode *temp=new BiNode;
		temp=bt->lchild;
		bt->lchild=bt->rchild;
		bt->rchild=temp;
		ExchangeTree(bt->lchild);
		ExchangeTree(bt->rchild);
	}
}
void Pre(BiNode *bt)
{
	if(bt==NULL)return;
	else {
		cout<<bt->data<<" ";
		Pre(bt->lchild);
		Pre(bt->rchild);
	}
}
int main()
{
	BiNode *root=CreateTree();
	ExchangeTree(root);
	Pre(root);
	return 0;
}