DataStructuresCSharp/C#/Datastructures/LinkedList/LinkedList.cs

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namespace C_.Datastructures.LinkedList
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{
public class LinkedList<T>
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{
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internal LinkedListNode<T>? Head { get; set; } = default;
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private int Count { get; set; } = 0;
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public static LinkedList<T> Create()
{
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//Create a new empty list
return new LinkedList<T>();
}
public static LinkedList<T> Create(T? value)
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{
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//Create a new Class with a single item
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return new LinkedList<T>()
{
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Head = LinkedListNode<T>.Create(value, null),
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Count = 1
};
}
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public static LinkedList<T> Create(LinkedList<T> list1, LinkedList<T> list2)
{
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//Append a previous list to a new List
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LinkedList<T> list;
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list = list1;
if (list == null || list.Count == 0) return list2;
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//Find end of list and append fist item of next list
if (list2 == null || list.Count == 0) return list;
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LinkedListNode<T>? end = list.Traverse();
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end!.Next = list2!.Head;
list.Count += list2!.Count;
return list;
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}
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public T? this[int i]
{
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get
{
//Check Range
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if (i >= Count || i < 0) throw new System.Exception("Error! Index out of Bounds");
//Return Value
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LinkedListNode<T>? node = Traverse(i);
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if (node != null) return node.Value;
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return default;
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}
set
{
//Check Range
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if (i >= Count || i < 0) throw new System.Exception("Error! Index out of Bounds");
//Change Value
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LinkedListNode<T>? node = Traverse(i);
node!.Value = value;
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}
}
public void Append(T? value)
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{
//Create new node
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Count++;
LinkedListNode<T> newItem = LinkedListNode<T>.Create(value, default);
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//Set head to new item if list is empty
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if (Head == null)
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{
Head = newItem;
return;
}
//Find last item in list
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LinkedListNode<T>? end = Head;
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if (end != null)
{
end = Traverse();
}
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//Append item to end
end!.Next = newItem;
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}
public void Insert(int index, T? value)
{
Count++;
if (index > Count || index < 0) throw new System.Exception("Error! Index outside of Bounds");
//Set head to new item if list is empty
if (index == 0 || Head == null)
{
Head = LinkedListNode<T>.Create(value, Head);
return;
}
//Fetch point in list at which item will be added
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LinkedListNode<T>? node = Traverse(index - 1);
node!.Next = LinkedListNode<T>.Create(value, node!.Next);
}
public void Delete(int index)
{
Count--;
if (index > Count || index < 0) throw new System.Exception("Error! Index outside of Bounds");
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//Check if we are trying to reference the first item
if (index == 0 && Head != default)
{
Head = Head!.Next;
return;
}
//Find node before the one we are trying to delete and then remove / relink
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LinkedListNode<T>? node = Traverse(index - 1);
node!.Next = node.Next!.Next;
}
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public int GetCount()
{//Return the number of items in the list
return Count;
}
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private LinkedListNode<T>? Traverse()
{
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//Start at Head of list
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LinkedListNode<T>? node = Head;
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if (node != null)
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{
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//continue to end of list
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while (node!.Next != default)
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{
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node = (LinkedListNode<T>)node.Next;
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}
}
return node;
}
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//private static LinkedListNode<T>? Traverse(LinkedListNode<T> start){
// //Start at given point in list
// LinkedListNode<T>? node = start;
// if (node != null)
// {
// //Continue to end of list
// while (node!.Next != default)
// {
// node = (LinkedListNode<T>)node.Next;
// }
// }
// return node;
//}
private LinkedListNode<T>? Traverse(int i)
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{
//Start at given point in list
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LinkedListNode<T>? node = Head;
if (node != null || i == 0)
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{
//Continue to end of list
for (int j = 0; j < i; j++)
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{
if (node!.Next == null) return null;
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node = (LinkedListNode<T>)node.Next;
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}
}
return node;
}
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}
}