From e1138917b4ed79027a13af837a9e94735d81a492 Mon Sep 17 00:00:00 2001
From: Tijmen van Nesselrooij <tijmen_222@hotmail.com>
Date: Wed, 1 May 2019 21:29:51 +0200
Subject: [PATCH] Linkedlist bugfixes

---
 sequential/linkedlist.hpp | 62 ++++++++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 24 deletions(-)

diff --git a/sequential/linkedlist.hpp b/sequential/linkedlist.hpp
index 7c9d3d9..9713a89 100644
--- a/sequential/linkedlist.hpp
+++ b/sequential/linkedlist.hpp
@@ -27,33 +27,35 @@ protected:
 public:
 	void Append(T const value)
 	{
-		++size;
-
-		if(tailPtr == nullptr)
+		if(size == 0)
 		{
 			root = std::make_unique<Node<T>>(value);
 			tailPtr = root.get();
+			++size;
 			return;
 		}
 
 		tailPtr->next = std::make_unique<Node<T>>(value);
 		tailPtr = tailPtr->next.get();
+
+		++size;
 	}
 
 	void Prepend(T const value)
 	{
-		++size;
-
-		if(root == nullptr)
+		if(size == 0)
 		{
 			root = std::make_unique<Node<T>>(value);
 			tailPtr = root.get();
+			++size;
 			return;
 		}
 
 		auto newRoot = std::make_unique<Node<T>>(value);
 		newRoot->next.swap(root);
 		root.swap(newRoot);
+
+		++size;
 	}
 
 	void Insert(T const value, std::size_t const index)
@@ -69,12 +71,6 @@ public:
 			return;
 		}
 
-		if(index == size - 1u)
-		{
-			Append(value);
-			return;
-		}
-
 		++size;
 
 		Node<T> * prevPtr = root.get();
@@ -83,7 +79,8 @@ public:
 		while(currentIndex < index)
 		{
 			prevPtr = curPtr;
-			curPtr = curPtr->next().get();
+			curPtr = curPtr->next.get();
+			++currentIndex;
 		}
 
 		auto newNode = std::make_unique<Node<T>>(value);
@@ -102,33 +99,43 @@ public:
 
 		if(index == 0u)
 		{
-			root.swap(root->next);
+			if(size == 0u)
+			{
+				root.release();
+				tailPtr = nullptr;
+			}
+			else
+			{
+				root = std::move(root->next);
+			}
 			return;
 		}
 
-		if(index == size - 1u)
+		// Is index last element? Note that we subtracted 1 from size above
+		if(index == size)
 		{
 			Node<T> * curPtr = root.get();
-			std::size_t currentIndex = 0u;
-			while(currentIndex < index - 2u)
+			while(curPtr->next.get() != tailPtr)
 			{
-				curPtr = curPtr->next().get();
+				curPtr = curPtr->next.get();
 			}
 
-			curPtr->next.release();
+			tailPtr = curPtr;
+			tailPtr->next.release();
 			return;
 		}
 
 		Node<T> * prevPtr = root.get();
-		Node<T> * curPtr = root->next.get();
+		Node<T> * curPtr = prevPtr->next.get();
 		std::size_t currentIndex = 1u;
 		while(currentIndex < index)
 		{
+			++currentIndex;
 			prevPtr = curPtr;
-			curPtr = curPtr->next().get();
+			curPtr = curPtr->next.get();
 		}
 
-		prevPtr->next.swap(curPtr->next);
+		prevPtr->next = std::move(curPtr->next);
 	}
 
 	T & Front()
@@ -159,18 +166,25 @@ public:
 		}
 
 		Node<T> * currentNode = root.get();
-		std:size_t currentIndex = 0u;
+		std::size_t currentIndex = 0u;
 		while(currentIndex < index)
 		{
 			currentNode = currentNode->next.get();
+			++currentIndex;
 		}
 
 		return currentNode->value;
 	}
 
+	std::size_t GetSize() const
+	{
+		return size;
+	}
+
 	List()
 		: root(nullptr),
-		tailPtr(nullptr)
+		tailPtr(nullptr),
+		size(0)
 	{}
 };
 }