206. Reverse Linked List

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

Follow up:

A linked list can be reversed either iteratively or recursively. Could you implement both?

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public ListNode reverseList(ListNode head) {
        if(head==null)
            return null;
        if (head.next == null)
            return head;
        ListNode node = reverseList(head.next);
        head.next.next=head;
        head.next=null;
        return node;
    }