From fd26fbb5507f8fe555ff06e958b5885a7edf6206 Mon Sep 17 00:00:00 2001
From: Shine wOng <1551885@tongji.edu.cn>
Date: Mon, 27 May 2019 16:52:16 +0800
Subject: [PATCH] add iterative post-traversal algorithm, tests passed.

---
 thu_dsa/chp5/binNode.h       | 26 ++++++++++++++++++++++++++
 thu_dsa/chp5/testBinTree.cpp |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/thu_dsa/chp5/binNode.h b/thu_dsa/chp5/binNode.h
index 9e02c22..35d7308 100644
--- a/thu_dsa/chp5/binNode.h
+++ b/thu_dsa/chp5/binNode.h
@@ -12,6 +12,7 @@ protected:
 	template <typename VST> 
 	void visitAlongLeftBranch(VST &visit, Stack<BinNodePosi(T)> &S);
 	void goAlongLeftBranch(Stack<BinNodePosi(T)> &S);
+	void goToHLVFL(Stack<BinNodePosi(T)> &S);							//Highest Leaf Visible From Left
 
 public:
 	BinNodePosi(T) parent;
@@ -63,6 +64,19 @@ void BinNode<T>::goAlongLeftBranch(Stack<BinNodePosi(T)> &S){
 	}
 }
 
+template <typename T>
+void BinNode<T>::goToHLVFL(Stack<BinNodePosi(T)> &S){
+	BinNodePosi(T) curr;
+	while(curr = S.top()){
+		if(curr->leftChild){
+			if (curr->rightChild) S.push(curr->rightChild);
+			S.push(curr->leftChild);
+		}
+		else S.push(curr->rightChild);
+	}
+	S.pop();
+}
+
 //public interfaces
 
 template <typename T>
@@ -151,6 +165,18 @@ void BinNode<T>::postOrder_Re(VST &visit){
 	visit(this->data);
 }
 
+template <typename T> template <typename VST>
+void BinNode<T>::postOrder_It(VST &visit){
+	Stack<BinNodePosi(T)> S;
+	BinNodePosi(T) curr = this;
+	S.push(curr);
+	while(!S.empty()){
+		if(S.top() != curr->parent) goToHLVFL(S);
+		curr = S.pop();
+		visit(curr->data);
+	}
+}
+
 template <typename T> template <typename VST>
 void BinNode<T>::levelOrder(VST &visit){
 	Queue<BinNodePosi(T)> q;
diff --git a/thu_dsa/chp5/testBinTree.cpp b/thu_dsa/chp5/testBinTree.cpp
index 3d50704..0af7703 100644
--- a/thu_dsa/chp5/testBinTree.cpp
+++ b/thu_dsa/chp5/testBinTree.cpp
@@ -130,6 +130,8 @@ void test_postTraversal(){
 
 	root->postOrder_Re(Print<int>());
 	cout << endl;
+	root->postOrder_It(Print<int>());
+	cout << endl;
 }
 
 void test_levelTraversal(){