From 4add56d7326d782e7de28809b2b5fcca0848bc19 Mon Sep 17 00:00:00 2001
From: Alessandro Ferro <49845537+xfarrow@users.noreply.github.com>
Date: Wed, 5 May 2021 10:03:25 +0200
Subject: [PATCH] Library 3

bugfix
---
 librerie/exercise3/binarytree/binarytree.cpp     | 16 +++++++++-------
 .../exercise3/binarytree/lnk/binarytreelnk.cpp   |  3 +++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/librerie/exercise3/binarytree/binarytree.cpp b/librerie/exercise3/binarytree/binarytree.cpp
index 5060d17..a5fdf86 100755
--- a/librerie/exercise3/binarytree/binarytree.cpp
+++ b/librerie/exercise3/binarytree/binarytree.cpp
@@ -292,19 +292,21 @@ void BTPreOrderIterator<Data>::operator++(){
   if(Terminated()) throw std::out_of_range("Iterator is terminated!");
 
   if(curr->HasLeftChild()){
-    curr = &(curr->LeftChild());
 
-    if( curr->HasRightChild() )
-      stack.Push(&curr->RightChild());
+    if( curr->HasRightChild() ){
+      stack.Push(&(curr->RightChild()));
+    }
+
+    curr = &(curr->LeftChild());
 
   }else if(curr->HasRightChild()){
     curr = &curr->RightChild();
   }
-  else{
-    try{
-      curr = stack.TopNPop();
-    }catch(std:: length_error exc){
+  else{ // is leaf
+    if(stack.Empty()){
       curr = nullptr;
+    }else{
+      curr = stack.TopNPop();
     }
   }
 }
diff --git a/librerie/exercise3/binarytree/lnk/binarytreelnk.cpp b/librerie/exercise3/binarytree/lnk/binarytreelnk.cpp
index a84a4e0..5b269f9 100755
--- a/librerie/exercise3/binarytree/lnk/binarytreelnk.cpp
+++ b/librerie/exercise3/binarytree/lnk/binarytreelnk.cpp
@@ -147,12 +147,15 @@ bool BinaryTreeLnk<Data>::operator!=(const BinaryTreeLnk<Data>& tree) const noex
 
 template <typename Data>
 struct BinaryTree<Data>::Node& BinaryTreeLnk<Data>::Root() const{
+  if(size==0) throw std::length_error("Empty tree!");
   return *root;
 }
 
 template <typename Data>
 void BinaryTreeLnk<Data>::Clear(){
   DeleteTree(root);
+  root = nullptr;
+  size = 0;
 }
 
 }