LinkedList

    class CustomSingleLinkedList<T>
    {
        private CustomLinkedListItem<T> rootNode;
        public int Count = 0;

        public void Add(T value)
        {
            CustomLinkedListItem<T> linkedListItem = new CustomLinkedListItem<T>(value);

            if (rootNode == null)
            {
                rootNode = linkedListItem;
                ++Count;
                return;
            }

            CustomLinkedListItem<T> previousNode = rootNode;

            while (previousNode.Reference != null)
            {
                previousNode = previousNode.Reference;               
            }

            previousNode.Reference = linkedListItem;
            ++Count;
        }


        public void InsertAt(T value, int position)
        {
            if (position > Count)
            {
                throw new IndexOutOfRangeException();
            }

            int tempCount = 0;
            CustomLinkedListItem<T> linkedListItem = new CustomLinkedListItem<T>(value);
            CustomLinkedListItem<T> node = rootNode;
            CustomLinkedListItem<T> tempnode = null;

            while (tempCount != position && node.Reference != null)
            {
                tempnode = node;
                node = node.Reference;
                tempCount++;
            }

            if (tempnode != null)
            {
                tempnode.Reference = linkedListItem;
            }
            else
            {
                this.rootNode = linkedListItem;
            }
           
            linkedListItem.Reference = node;          
        }

        public void ChangeValueAt(int position, T value)
        {
            int tempCount = 1;
            CustomLinkedListItem<T> node = rootNode;

            while (tempCount != position && node.Reference != null)
            {
                node = node.Reference;
                tempCount++;
            }

            node.Item = value;
        }

        public T ValueAt(int position)
        {
            T value = default(T);

            int tempCount = 1;
            CustomLinkedListItem<T> node = rootNode;

            while (tempCount != position && node.Reference != null)
            {
                node = node.Reference;
                tempCount++;
            }

            value = node.Item;
            return value;
        }

        public void ReverseLinkedList()
        {
            int tempCount = Count;

            for (int i = 1, j = tempCount; i < j; i++, j--)
            {
                T Temp = ValueAt(i);
                ChangeValueAt(i, ValueAt(j));
                ChangeValueAt(j, Temp);
            }
        }

        public T ReturnLastItem()
        {
            if (rootNode == null)
            {
                throw new InvalidOperationException("Root node is null");
            }

            if (rootNode.Reference == null)
            {
                return rootNode.Item;
            }

            CustomLinkedListItem<T> node = rootNode;

            while (node.Reference != null)
            {
                node = node.Reference;
            }

            return node.Item;
        }

        public void RemoveLastItem()
        {
            if (rootNode == null)
            {
                throw new InvalidOperationException("Root node is null");
            }

            if (rootNode.Reference == null)
            {
                rootNode = null;
                return;
            }

            CustomLinkedListItem<T> node = this.rootNode;
            CustomLinkedListItem<T> tempnode = null;

            while (node.Reference != null)
            {
                tempnode = node;
                node = node.Reference;
            }

            tempnode.Reference = null;
        }

        public void RemoveFirstItem()
        {
            if (rootNode == null)
            {
                throw new InvalidOperationException("Root node is null");
            }

            if (rootNode.Reference != null)
            {
                rootNode = rootNode.Reference;
            }
            else
            {
                rootNode = null;
            }
        }       
    }

    class CustomLinkedListItem<T>
    {
        public T Item { set; get; }
        public CustomLinkedListItem<T> Reference { set; get; }

        public CustomLinkedListItem(T item)
        {
            this.Item = item;
        }
    }