CareerCup

public Node reverseIterative(Node head) {
		Node current = head;
		Node next = current.next;
		current.next = null;
		Node temp;
		while (next != null) {
			temp = next.next;
			next.next = current;
			current = next;
			next = temp;
		}
		return current;
	}

	public Node reverseRecursive(Node head) {
		if (head.next == null)
			return head;
		Node oldNext = head.next;
		Node newHead = reverseRecursive(head.next);
		oldNext.next = head;
		head.next = null;
		return newHead;
	}

Iterative Approach:
let the pointer 'second' points to first node , the pointer 'first' points to second node and the pointer 'third' points to null.

while(second!=null)
{
     second -> next = third;
     first -> next = second;
     third = second;
    second = first;
    first = first -> next;
}

A recursive approach:

rev(root)
{
	if(!root || !(root->next))
		newroot=root;
	else
	{
		rev(root->next);
		if(root->next)
		{
			root->next->next=root;
			root->next=NULL;
		}
	}
	return newroot;
}

An iterative one:

iterativerev(root)
{
	Node *p,*q,*r;
	q=root;
	while(q)
	{
		r=q->next;
		q->next=p;
		p=q;
		q=r;
	}
	return p;
}

public static void Reverse(ref Node<int> head)
        {

            Node<int> first;
            Node<int> rest;
            if (head == null) return;
            first = head;
            rest = first.NextNode;
            if (rest == null) return;
            Reverse(ref rest);
            first.NextNode.NextNode = first;
            first.NextNode = null;
            head = rest;

}

/////////// iterative

LinkNode *reverseLink(LinkNode *head)
{
if(head == NULL)
return NULL;
if(head->next == NULL)
return head;
if(head->next->next == NULL)
{
LinkNode *tail = head->next;
head->next->next = head;
head->next = NULL;
return tail;
}

LinkNode *pre = head;
LinkNode *current = head->next;
LinkNode *next = head->next->next;

while(next != NULL)
{
current->next = pre;
pre = current;
current = next;
next = next->next;
}
head->next = NULL;
current->next = pre;
return current;
}

////////////recursive

LinkNode *reverseLink(LinkNode *head)
{
if(head == NULL)
return NULL;
if(head->next == NULL)
return head;

LinkNode *next = reverseLink(head->next);
next->next = head;
head->next = NULL;
return head;
}