Leetcode 206 : https://leetcode.com/problems/reverse-linked-list/

ReverseLinkedList.java

public 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;
  }
}