public static SingleLinkedListNode RemoveDuplicatesFromSortedListII(this SingleLinkedListNode head)
{
if (head is null)
{
return(head);
}
var dummy = new SingleLinkedListNode(-1);
dummy.Next = head;
var prev = dummy;
while (head != null)
{
if (head.Next != null && head.Data == head.Next.Data)
{
while (head.Next != null && head.Data == head.Next.Data)
{
head = head.Next;
}
prev.Next = head.Next;
}
else
{
prev = prev.Next;
}
head = head.Next;
}
return(dummy.Next);
}
public static SingleLinkedListNode SwapNodePairs(this SingleLinkedListNode node)
{
if (node is null)
{
return(node);
}
SingleLinkedListNode dummy = new SingleLinkedListNode(-1);
dummy.Next = node;
SingleLinkedListNode prev = dummy;
while (node != null && node.Next != null)
{
var firstNode = node;
var secondNode = node.Next;
prev.Next = secondNode;
firstNode.Next = secondNode.Next;
secondNode.Next = firstNode;
prev = firstNode;
node = firstNode.Next;
}
return(dummy.Next);
}
public static SingleLinkedListNode DeleteNthNodeFromEnd(this SingleLinkedListNode node, int n)
{
if (node is null)
{
return(node);
}
SingleLinkedListNode dummy = new SingleLinkedListNode(-1);
dummy.Next = node;
SingleLinkedListNode slow = dummy;
SingleLinkedListNode fast = dummy;
while (n + 1 >= 1)
{
fast = fast.Next;
n--;
}
while (fast != null)
{
slow = slow.Next;
fast = fast.Next;
}
if (slow.Next == null)
{
slow.Next = null;
}
else
{
slow.Next = slow.Next.Next;
}
return(dummy.Next);
}
public static SingleLinkedListNode ReorderList(this SingleLinkedListNode head)
{
if (head is null)
{
return(head);
}
SingleLinkedListNode current = head;
SingleLinkedListNode test = head;
SingleLinkedListNode reversed = current.Reverse();
int length = head.Length;
int count = 0;
current = head;
while (reversed != null && count < ((length) / 2))
{
SingleLinkedListNode rnext = reversed.Next;
SingleLinkedListNode cnext = current.Next;
current.Next = reversed;
reversed.Next = cnext;
reversed = rnext;
current = cnext;
count++;
}
return(head);
}
public static SingleLinkedListNode ReverseInplace(this SingleLinkedListNode node)
{
SingleLinkedListNode current = node, prev = null, next = null;
while (current != null)
{
next = current.Next;
current.Next = prev;
prev = current;
current = next;
}
return(prev);
}
public static SingleLinkedListNode Copy(this SingleLinkedListNode node)
{
SingleLinkedListNode newNode = new SingleLinkedListNode(node.Data);
SingleLinkedListNode current = newNode;
node = node.Next;
while (node != null)
{
SingleLinkedListNode n2 = new SingleLinkedListNode(node.Data);
current.Next = n2;
current = n2;
node = node.Next;
}
return(newNode);
}
public override bool Equals(object obj)
{
var node1 = this;
SingleLinkedListNode node = obj as SingleLinkedListNode;
while (node1 != null && node != null)
{
if (node1.Data != node.Data)
{
return(false);
}
node1 = node1.Next;
node = node.Next;
}
if (node is null && node1 is null)
{
return(true);
}
return(false);
}
public static SingleLinkedListNode Add(this SingleLinkedListNode node1, SingleLinkedListNode node2)
{
SingleLinkedListNode reversedNode1 = node1.ReverseInplace();
SingleLinkedListNode reversedNode2 = node2.ReverseInplace();
SingleLinkedListNode dummy = new SingleLinkedListNode(-1);
SingleLinkedListNode sumNode = dummy;
int carry = 0;
while (reversedNode1 != null || reversedNode2 != null)
{
int sum = (reversedNode1?.Data ?? 0) + (reversedNode2?.Data ?? 0) + carry;
carry = sum / 10;
sumNode.Next = new SingleLinkedListNode(sum % 10);
sumNode = sumNode.Next;
reversedNode1 = reversedNode1?.Next;
reversedNode2 = reversedNode2?.Next;
}
if (carry > 0)
{
sumNode.Next = new SingleLinkedListNode(carry);
}
return(dummy.Next.ReverseInplace());
}
public static SingleLinkedListNode DeleteDuplicates(this SingleLinkedListNode node)
{
if (node is null)
{
return(node);
}
HashSet <int> nums = new HashSet <int>();
SingleLinkedListNode current = node, prev = node;
while (current != null)
{
if (nums.Contains(current.Data))
{
prev.Next = current.Next;
}
else
{
nums.Add(current.Data);
prev = current;
}
current = current.Next;
}
return(node);
}
public SingleLinkedList()
{
_length = 0;
_head = null;
}