编写复制一颗二叉树的非递归算法

问题描述：设栈的类型为seqstack，initstack(s)为对栈s初始化。

基本思路：用两个栈保存左右树访问的节点，每次访问根后PUSH一下，然后pop出继续保存左右子树。

// CopyBinaryTrees.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdlib.h>
#include <iostream>
#include <Windows.h>

using namespace std;

typedef char element;

typedef struct bitree
{
element data;
struct bitree* lchild;
struct bitree* rchild;
}bitree;

typedef struct node
{
bitree* data;
struct node *next;
}node,*pnode;

class seqstack
{
private:
node* top;//当前位置,头结点
public:
void initstack();
void push(bitree* bt);
BOOL pop(bitree* &bt);
BOOL isempty();//栈是否为空，空返回true，非空返回false
};
void seqstack::initstack()
{
top = NULL;
}
void seqstack::push(bitree* bt)
{
node* p = (node*)malloc(sizeof(node));
p->data = bt;
p->next = top;
top = p;
}
BOOL seqstack::pop(bitree* &bt)
{
node* p;
if( isempty()) // 堆栈为空，删除失败，返回0
return FALSE;
else{
p = top;
bt = p->data; // 将栈顶元素数据域送入item中
p->next = NULL;
top = top->next; // 修改栈顶指针
free( p ); // 释放被删除结点
return TRUE; // 操作成功，返回1
}
}
BOOL seqstack::isempty()
{
if (top == NULL)
return true;
else
return false;
}

void CreateBiTree(bitree* &T)
{
char ch;
cin>>ch;
if(ch=='#') T=NULL;
else
{
T=(bitree *)malloc(sizeof(bitree));
T->data=ch;
T->lchild = NULL;
T->rchild = NULL;
cout<<"put in \'"<<T->data<<"\' lchild"<<endl;
CreateBiTree(T->lchild);
cout<<"put in \'"<<T->data<<"\' rchild"<<endl;
CreateBiTree(T->rchild);
}
}//CreateBiTree

bitree* copyBinaryTree(bitree *bSrc)
{
seqstack stack_left,stack_right;
bitree* newbt;
if (bSrc!=NULL)
{
//new root
newbt=new bitree;
newbt->data=bSrc->data;
newbt->lchild = NULL;
newbt->rchild = NULL;
//travel bt and travel newbt at the same time
stack_left.push(bSrc);
stack_right.push(newbt);
while (!stack_left.isempty())
{
bitree* pleft;
stack_left.pop(pleft);
bitree* pright;
stack_right.pop(pright);
if (pleft->rchild!=0)
{
stack_left.push(pleft->rchild);
pright->rchild=new bitree;
pright->rchild->data=pleft->rchild->data;
pright->rchild->lchild = NULL;
pright->rchild->rchild = NULL;
stack_right.push(pright->rchild);
}
if (pleft->lchild!=0)
{
stack_left.push(pleft->lchild);
pright->lchild=new bitree;
pright->lchild->data=pleft->lchild->data;
pright->lchild->lchild = NULL;
pright->lchild->rchild = NULL;
stack_right.push(pright->lchild);
}
}
}
return newbt;
}

int _tmain(int argc, _TCHAR* argv[])
{

printf("enter # is over,put in root node\n");
bitree *b1 = (bitree *)malloc(sizeof(bitree));
CreateBiTree(b1);
bitree* b2 = copyBinaryTree(b1);
return 0;
}