Reverse Linked List

Given the head of a singly linked list, reverse the list, and return the reversed list.

 

Example 1:

Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]

Example 2:

Input: head = [1,2]
Output: [2,1]

Example 3:

Input: head = []
Output: []

Solution

/**

* Definition for singly-linked list.

* public class ListNode {

* int val;

* ListNode next;

* ListNode() {}

* ListNode(int val) { this.val = val; }

* ListNode(int val, ListNode next) { this.val = val; this.next = next; }

* }

*/

class Solution {

public ListNode reverseList(ListNode head) {

ListNode prev = null;

ListNode current = head;

while(current!=null) {

ListNode next = current.next;

current.next = prev;

prev = current;

current = next;

}

return prev;

}

}