/// <summary>
/// Time Complexity is O(n^2). Space Complexity is 1
/// </summary>
/// <returns></returns>
public object BrutalForceMethod(SingleLinkedList list, int n)
{
if (list.Head == null)
{
return null;
}
LinkedListNode current = list.Head;
LinkedListNode temp = current;
int remainingNodes = 0;
while (temp.Next != null)
{
remainingNodes++;
if (remainingNodes >= n)
{
current = current.Next;
temp = current;
remainingNodes = 0;
}
else
{
temp = temp.Next;
}
}
if (remainingNodes == n - 1)
{
return current;
}
else
{
return null;
}
}
/// <summary>
/// Time Complexity is O(n). Space Complexity is O(n)
/// </summary>
/// <returns></returns>
public object UsingLength(SingleLinkedList list, int n)
{
if (list.Head == null)
{
return null;
}
var current = list.Head;
int l = 1;
//calculate length
while (current.Next != null)
{
l++;
current = current.Next;
}
int i = l - n + 1;
if (i > 0)
{
current = list.Head;
while (i > 1)
{
current = current.Next;
i--;
}
return current;
}
return null;
}
public void Intialize()
{
list = new SingleLinkedList();
list.AddFront(3);
list.AddFront(2);
list.AddFront(1);
list.Print();
}
public void TestReverseRecursive()
{
Console.WriteLine("Test started!");
ReverseList reverse = new ReverseList();
list = reverse.ReverseLinkedListRecursive(list);
Console.WriteLine("Reverse Ended!");
list.Print();
Console.WriteLine("Test Ended!");
}
public void Intialize()
{
EmptyList = new SingleLinkedList();
SingleNodeList = new SingleLinkedList();
SingleNodeList.AddLast(1);
List = new SingleLinkedList();
List.AddLast(1);
List.AddLast(2);
List.AddLast(3);
List.AddLast(4);
List.AddLast(5);
List.AddLast(6);
}
public SingleLinkedList ReverseLinkedListRecursive(SingleLinkedList list)
{
if(list.Head == null) return list;
var head = list.Head;
var tail = list.Tail;
ReverseNodes(list.Head);
list.Tail = head;
list.Head = tail;
return list;
}
public SingleLinkedList ReverseLinkedListIterative(SingleLinkedList list)
{
Console.WriteLine("Reverse Started!");
if(list.Head == null) return null;
LinkedListNode current = list.Head;
LinkedListNode previous = null;
LinkedListNode next = current.Next;
while(current != null)
{
next = current.Next;
current.Next = previous;
previous = current;
current = next;
}
list.Head = previous;
return list;
}
public object UsingHashTable(SingleLinkedList list, int n)
{
if (list.Head == null)
{
return null;
}
Hashtable table = new Hashtable();
var current = list.Head;
for (int i = 1; current != null; i++)
{
table.Add(i,current);
current = current.Next;
}
int x = table.Count - n + 1;
if (x > 0)
{
return table[x];
}
return null;
}
public object UsingRangeMethod(SingleLinkedList list, int n)
{
if (list.Head == null)
{
return null;
}
var first = list.Head;
var last = list.Head;
for (int i = 1; i < n; i++)
{
if (last.Next != null)
{
last = last.Next;
}
else
{
return null;
}
}
while (last.Next != null)
{
last = last.Next;
first = first.Next;
}
return first;
}
public SingleLinkedListTests()
{
List = new SingleLinkedList();
}