Reverse Linked List

Reverse a singly linked list.

Recursive method

/** * Definition for singly-linked list. * public class ListNode {*     int val; *     ListNode Next; *     listnode (int x) {val = x;}}} */public class Soluti On {public    ListNode reverselist (ListNode head) {    return reverselist (null, head);    }        Private ListNode reverselist (ListNode left,listnode right) {    if (right==null) return to left;    ListNode rnext = Right.next;    Right.next = left;    Return Reverselist (Right,rnext);}    }

Iterative methods

/** * Definition for singly-linked list. * public class ListNode {*     int val; *     ListNode Next; *     listnode (int x) {val = x;}}} */public class Soluti On {public    ListNode reverselist (ListNode head) {    if (head==null) return head;        ListNode lefthead = null;        ListNode current = head;        ListNode nxt = Head.next;        while (current!=null) {        current.next = Lefthead;        Lefthead = current;        current = NXT;        if (current==null) break;        NXT = Nxt.next;        }        return lefthead;}    }

Reverse Linked List