二叉树的非递归先序，中序，后序遍历

二叉树的非递归遍历：

        先序遍历，中序遍历，后序遍历

#include <iostream>
#include <stack>

using namespace std;

typedef struct node
{
    char data;
    struct node *lchild;
    struct node *rchild;
} BiNode, *BiTree;

//先序递归创建树，这里注意参数的类型，T的类型是 "*&" ,如果是 "**" 代码稍加改动就OK...
void createTree(BiTree &T) 
{
	char ch;
	cin.get(ch).get(); 
	//过滤输入流中每次回车产生的回车符 
	if (ch==' ')
		T = NULL; //这里首先判断是不是空格，如果是，则为该节点赋NULL 
	else 
	{
		T = (BiTree)malloc(sizeof(BiNode)); 
		T->data = ch; 
		createTree(T->lchild); 
		createTree(T->rchild); 
	}
}

void preOrderNoRe(BiTree T) // 前序遍历
{
	if( T == NULL) 
	{ 
		return ; 
	} 
	stack<BiTree> s; 
	BiTree p = NULL;
	p = T; 
	while( p != NULL || !s.empty()) 
	{
		while (p != NULL) 
		{
			cout<< p->data <<" "; 
			s.push(p); 
			p = p->lchild; 
		} 
		
		if(!s.empty()) 
		{ 
			p = s.top(); 
			s.pop(); 
			p = p->rchild; 
		} 
	}
}

void inOrderNoRe(BiTree T) //中序遍历
{ 
	if( T == NULL)
	{
		return ; 
	}
	stack<BiTree> s; 
	BiTree p = NULL;
	p = T; 
	while(p != NULL || !s.empty()) 
	{
		while (p != NULL)
		{
			s.push(p); 
			p = p->lchild; 
		}
		if (!s.empty()) 
		{
			p = s.top();
			s.pop(); 
			cout << p->data <<" "; p = p->rchild; 
		} 
	}
}

void postOrderNoRe(BiTree T) //后序遍历
{
	if( T == NULL) 
	{
		return ; 
	} 
	
	BiTree p = NULL;
	stack<BiTree> s;
	p = T; 
	int Tag[200]; // 栈，用于标识从左（0）或右（1）返回 
	int top = -1; 
	while ( p != NULL || !s.empty())
	{
		while( p != NULL) 
		{
			s.push(p); 
			Tag[++top] = 0; 
			p = p->lchild; 
		} 
		
		while ( !s.empty() && Tag[top] == 1) 
		{
			p = s.top(); 
			s.pop(); 
			cout<< p->data << " "; --top; // 出栈 
		} 
		if (!s.empty()) 
		{ 
			Tag[top] = 1; //设置标记右子树已经访问 
			p = s.top(); 
			p = p->rchild; 
		} 
		else
		{
			break; 
		} 
	}
}

int main()
{
	cout<<"Enter char one by one"<<endl;
	BiNode *T; 
	createTree(T); 
	cout<<endl; 
	
	cout<<"preOrderNoRe: ";
	preOrderNoRe(T);
	cout<<endl; 
	cout<<"inOrderNoRe: ";
	inOrderNoRe(T);
	cout<<endl; 
	
	cout<<"postOrderNoRe: ";
	postOrderNoRe(T);
	cout<<endl;
	
	system("pause"); 
	return 0;
}

By Andy @2013-09-08