二叉树的三种递归与非递归遍历

递归遍历

#include<iostream>
using namespace std;
typedef struct BinTree
{
	ElemType data;
	struct BinTree* Left;
	struct BinTree* Right;
}BinTree;
void PostOrderTraversal(BinTree* BT)//完全二叉树递归遍历
{
	if(Bt)
	{
		//cout<<BT->data<<" ";前序
		PostOrderTraversal(BT->Left);
		//cout<<BT->data<<" ";中序
		PostOrderTraversal(BT->Right);
		//cout<<BT->data<<" ";后序
	}
}

非递归遍历

#include<iostream>
using namespace std;
typedef struct BinTree
{
	ElemType data;
	struct BinTree* Left;
	struct BinTree* Right;
}BinTree;
//省去了堆栈和二叉树的创建函数
void PostOrderTraversal(BinTree* BT)//二叉树中序堆栈遍历
{
	BinTree* T=BT;
	stack* S=CreatStack();//创建堆栈并初始化
	while(T||!IsEmpty(S))
	{
		while(T)//将沿途结点压入堆栈，一直向左
		{
			//cout<<T->data<<" ";先序遍历
			push(S,T);
			T=T->Left;
		}
		if(!Isempty(S))
		{
			T=Pop(S);//弹出结点堆栈
			//cout<<T->data<<" ";中序遍历
			T=T->Right;//转向右子树
		}
	}
}
void PostorderTraversal(BinTree* T)//二叉树的后序堆栈遍历
{
	BinTree *T, *r=NULL;
	Stack S = CreateStack();
	T = BT; r = NULL;
	while (T || !IsEmpty(S)) {
		if (T) {
			Push(S, T);
			T = T->Left;
		}
		else {
			T = Pop(S);
			if (T->Right && T->Right != r) {//右子树存在，则子树访问完全
				T = T->Right;
			}
			else {
				Pop(S);
				cout<<T->data<<" ";
				r = T;//记录访问过的结点
				T = NULL;//结点访问完之后重置
			}
		}
	}
}