c++考研复习之非递归前序中序后序遍历二叉树

/*
 * =====================================================================================
 *
 *       Filename:  Stack.h
 *
 *    Description:  栈类
 *
 *        Version:  1.0
 *        Created:  2013年11月13日 21时38分49秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  dependmyse (lxy), dependmyse@gmail.com
 *        Company:  TianJin University
 *
 * =====================================================================================
 */
#ifndef _STACK_H_
#define _STACK_H_
#include <iostream> 
#define MAXSIZE 50
#include <iostream>
using namespace std;
//定义二叉树结构体
typedef struct TreeNode {
    char data;
    TreeNode *lChild;
    TreeNode *rChild;
}TreeNode,*Tree;

class Stack{
    public:
        int getTop();
        void push(TreeNode *data);
        TreeNode * pop();
        bool isStackEmpty();
        bool isStackFull();
        void initStack();
        TreeNode *getTopPtr();
    private:
        int top;
        Tree *content;
};
void Stack::initStack()
{
    content=new Tree[MAXSIZE]; 
    top=-1;
}

bool Stack::isStackEmpty()
{
    return top==-1;
}
bool Stack::isStackFull()
{
    return top==MAXSIZE;
}
void Stack::push(TreeNode *data)
{
   if(isStackFull()) 
   {
       cout<<"栈已满，无法继续插入"<<endl;
       return;
   }else
   {
       this->content[++top]=data;
   }
}
TreeNode* Stack::pop()
{
    if(isStackEmpty())
    {
        cout<<"栈已空，无法继续删除"<<endl;
        return NULL;
    }else
    {
        return this->content[top--];
    }
}
int Stack::getTop()
{
    return this->top;
}
TreeNode* Stack::getTopPtr()
{
    return this->content[top];
}
#endif

/*
 * =====================================================================================
 *
 *       Filename:  TravelTreeByStack.cpp
 *
 *    Description: 使用栈分别前中后对二叉树进行遍历 
 *
 *        Version:  1.0
 *        Created:  2013年11月13日 21时22分39秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  dependmyse (lxy), dependmyse@gmail.com
 *        Company:  TianJin University
 *
 * =====================================================================================
 */
#include "Stack.h"
#include <iostream>
using namespace std;
/*typedef struct TreeNode {
    char data;
    TreeNode *lChild;
    TreeNode *rChild;
}TreeNode;*/

//递归创建二叉树
TreeNode *createTree()
{
    char data;
    TreeNode *treeNode;
    cin>>data;
    if(data!='#')
    {
        treeNode=new TreeNode();
        treeNode->data=data;
        cout<<"输入左节点的值"<<endl;
        treeNode->lChild=createTree();
        cout<<"输入右节点的值"<<endl;
        treeNode->rChild=createTree();
    }else{
        treeNode=NULL;
    }
    return treeNode;
}
void visit(TreeNode *treeNode)
{
    cout<<treeNode->data<<" ";
}
//递归先序遍历
void preOrder(TreeNode *root)
{
    if(root!=NULL)
    {
        visit(root);
        preOrder(root->lChild);
        preOrder(root->rChild);
    }
}
//非递归先序遍历
void preOrderByStack(TreeNode *root)
{
    Stack stack;
    stack.initStack();
    TreeNode *p=root;
    TreeNode *temp;
    while(p!=NULL||!stack.isStackEmpty())
    {
        while(p!=NULL)
        {
            visit(p);
            stack.push(p);
            p=p->lChild;
        }
        if(!stack.isStackEmpty())
        {
            temp=stack.pop();      
            p=temp->rChild;
        }
    }
}
//非递归中序遍历
void inOrderByStack(TreeNode *root)
{
    Stack stack;
    stack.initStack();
    TreeNode *p=root;
    TreeNode *temp;
    while(p!=NULL||!stack.isStackEmpty())
    {
        while(p!=NULL)
        {
            stack.push(p);
            p=p->lChild;
        }
        if(!stack.isStackEmpty())
        {
            temp=stack.pop();
            visit(temp);
            p=temp->rChild;
        }
    }
}
//非递归后续遍历
void postOrder(TreeNode *root)
{
    Stack stack;
    stack.initStack();
    //定义标志变量，标记结点是第几次被访问，第二次被访问时
    //标记变量设为1输出，否则为0
    int flags[MAXSIZE];
    TreeNode *p=root;
    TreeNode *temp;
    while(p!=NULL||!stack.isStackEmpty())
    {
        while(p!=NULL)
        {
            stack.push(p);
            flags[stack.getTop()]=0;
            p=p->lChild;
        }
        while(!stack.isStackEmpty()&&flags[stack.getTop()]==1)
        {
            temp=stack.pop();
            visit(temp);
        }
        if(!stack.isStackEmpty())
        {
            temp=stack.getTopPtr();    
            flags[stack.getTop()]=1;
            p=temp->rChild;
        }
    }
}
int main()
{
    TreeNode *treeNode=createTree();
    //preOrder(treeNode);
    cout<<"非递归先序遍历"<<endl;
    preOrderByStack(treeNode);
    cout<<endl;
    cout<<"非递归中序遍历"<<endl;
    inOrderByStack(treeNode); 
    cout<<endl;
    cout<<"非递归后续遍历"<<endl;
    postOrder(treeNode);
    cout<<endl;
    return 0;
}

程序运行效果如下图所示