From 584f7c3003ec82b1d4a8129976733f2bbb3d87e5 Mon Sep 17 00:00:00 2001
From: Alessandro Ferro <49845537+xfarrow@users.noreply.github.com>
Date: Wed, 19 May 2021 10:58:54 +0200
Subject: [PATCH] Library 4

---
 librerie/exercise4/bst/bst.cpp      | 31 ++++++++-----
 librerie/exercise4/zmytest/test.cpp | 71 ++++++++++++++++-------------
 librerie/exercise4/zmytest/test.hpp |  2 +-
 3 files changed, 60 insertions(+), 44 deletions(-)

diff --git a/librerie/exercise4/bst/bst.cpp b/librerie/exercise4/bst/bst.cpp
index 3cf96fb..db91a14 100755
--- a/librerie/exercise4/bst/bst.cpp
+++ b/librerie/exercise4/bst/bst.cpp
@@ -262,7 +262,7 @@ template <typename Data>
 typename BST<Data>::NodeLnk* const& BST<Data>::FindPointerToMax(struct BST<Data>::NodeLnk* const& node) const noexcept{
   NodeLnk* const* ptr = &node;
   NodeLnk* curr = node;
-  if(curr!=nullptr){ 
+  if(curr!=nullptr){
     while(curr->right != nullptr){
       ptr = &curr->right;
       curr = curr->right;
@@ -283,21 +283,28 @@ typename BST<Data>::NodeLnk* const& BST<Data>::FindPointerTo(struct BST<Data>::N
     declare a variable (pointer) which points to a const pointer which points to
     a NodeLnk.
     This const pointer that points to a NodeLnk is the parameter of the function.
+    Hence, (*pointer) will be a const pointer.
 
-    Hence, *pointer will be a const pointer.
+    Note: this function (and others too) could've been written using one single pointer, in this way:
+    while(*pointer != nullptr && (*(*pointer)).Element() != data){
+      if( (*(*pointer)).Element() < data ) pointer = &((*pointer)->right);
+      else if((*(*pointer)).Element() > data ) pointer = &((*pointer)->left);
+    }
+    but I preferred to use a clearer version.
   */
+
   NodeLnk* const* pointer = &ref; //a pointer to a const pointer to a NodeLnk
   NodeLnk* current = ref;
 
-    while(current != nullptr && current->Element() != data){
-      if(current->Element() < data){
-        pointer = &(current->right);
-        current = current->right;
-      }else if(current->Element() > data){
-        pointer = &(current->left);
-        current = current->left;
-      }
+  while(current != nullptr && current->Element() != data){
+    if(current->Element() < data){
+      pointer = &(current->right);
+      current = current->right;
+    }else if(current->Element() > data){
+      pointer = &(current->left);
+      current = current->left;
     }
+  }
   return *pointer;
 }
 
@@ -307,10 +314,10 @@ typename BST<Data>::NodeLnk* const* BST<Data>::FindPointerToPredecessor(struct B
   /*
     If the element we are looking the predecessor for is the current element,
     then its predecessor resides in the max node of its left subtree (if it has
-    a left subtree. Return the lastRight otherwise).
+    a left subtree. Return the candidate otherwise).
 
     If the element we are looking the predecessor for is greater than the current element,
-    then we have to go down right the tree, saving the current "lastRight".
+    then we have to go down right the tree, saving the current "candidate".
 
     If the element we are looking the predecessor for is less than the current element,
     then we have to go down left the tree.
diff --git a/librerie/exercise4/zmytest/test.cpp b/librerie/exercise4/zmytest/test.cpp
index 997cc6f..87a6179 100755
--- a/librerie/exercise4/zmytest/test.cpp
+++ b/librerie/exercise4/zmytest/test.cpp
@@ -328,8 +328,8 @@ void StringFunctions(BST<Data>& bst){
     std::cout<<" 18. Node-level operations (debug)"<<std::endl;
     std::cout<<" 19. Go back"<<std::endl;
     std::cout<<" 20. Quit"<<std::endl;
-
     cout<<endl<<" -> ";
+
     std::cin>>std::ws;
     std::cin>>choice;
     std::cout<<std::endl;
@@ -604,40 +604,49 @@ void RemoveSuccessor(BST<Data>& bst){
 }
 
 template <typename T>
-void NodeOperations(T& currentNode){
+bool NodeOperations(T& currentNode){
   uint choice;
+  bool wantToExit = false;
   cout<<endl<<endl;
-  cout<<" *** Element in the current node: "<<currentNode.Element()<<" ***"<<endl;
-  cout<<" 1. Go left"<<endl;
-  cout<<" 2. Go Right"<<endl;
-  cout<<" 3. Is this a leaf?"<<endl;
-  cout<<" 4. Go back"<<endl;
-  cout<<endl<<" -> ";
-  cin>>ws;
-  cin>>choice;
-  switch(choice){
-    case 1:
-      if(currentNode.HasLeftChild()) NodeOperations(currentNode.LeftChild());
-      else{
-        cout<<"\nThe node does not have a left child, operation aborted.";
-        NodeOperations(currentNode);
-      }
-      break;
+  do{
+    cout<<" *** Element in the current node: "<<currentNode.Element()<<" ***"<<endl;
+    cout<<" 1. Go left"<<endl;
+    cout<<" 2. Go Right"<<endl;
+    cout<<" 3. Is this a leaf?"<<endl;
+    cout<<" 4. Go up"<<endl;
+    cout<<" 5. Go to menu"<<endl;
+    cout<<endl<<" -> ";
+    cin>>ws;
+    cin>>choice;
+    switch(choice){
+      case 1:
+        if(currentNode.HasLeftChild()){
+          wantToExit = NodeOperations(currentNode.LeftChild());
+        }
+        else{
+          cout<<"\nThe node does not have a left child, operation aborted.\n";
+        }
+        break;
 
-    case 2:
-      if(currentNode.HasRightChild()) NodeOperations(currentNode.RightChild());
-      else {
-        cout<<"\nThe node does not have a right child, operation aborted.";
-        NodeOperations(currentNode);
-      }
-      break;
+        case 2:
+          if(currentNode.HasRightChild()){
+            wantToExit = NodeOperations(currentNode.RightChild());
+          }
+          else {
+            cout<<"\nThe node does not have a right child, operation aborted.\n";
+          }
+          break;
 
-    case 3:
-      if(currentNode.IsLeaf()) cout<<"\n Yes, the current node is a leaf";
-      else cout<<"\n No, the current node is not a leaf";
-      NodeOperations(currentNode);
-      break;
+        case 3:
+          if(currentNode.IsLeaf()) cout<<"\n Yes, the current node is a leaf\n";
+          else cout<<"\n No, the current node is not a leaf\n";
+          break;
+
+        case 4:
+          return false;
     }
+  }while(choice!=5 && !wantToExit);
+  return true;
 }
 
 
@@ -650,7 +659,7 @@ BST<int> GenerateIntegerBST(BST<int>& bst){
   default_random_engine gen(random_device{}());
   uniform_int_distribution<int> dist(0,1000);
 
-  cout<<"\n\nElements in the binary tree (in breadth order):\n";
+  cout<<"\n\nElements in the binary tree (in order of insertion):\n";
   for(ulong i=0 ; i<dim ; ++i){
     tmp[i] = dist(gen);
     cout<<tmp[i]<<" ";
diff --git a/librerie/exercise4/zmytest/test.hpp b/librerie/exercise4/zmytest/test.hpp
index 590f9c6..7d5284d 100755
--- a/librerie/exercise4/zmytest/test.hpp
+++ b/librerie/exercise4/zmytest/test.hpp
@@ -92,7 +92,7 @@ template <typename Data>
 void RemoveSuccessor(lasd::BST<Data>&);
 
 template <typename T>
-void NodeOperations(T&);
+bool NodeOperations(T&);
 
 
 /* ----- generator functions ----- */