LF.33.number Of Nodes

 1 public class Solution {
 2   public int numberOfNodes(ListNode head) {
 3     // Write your solution here
 4     if (head == null) {
 5         return 0;
 6     }
 7     int res = 0;
 8     ListNode curr = head ;
 9     while(curr != null){
10         curr = curr.next ;
11         res++;
12     }
13     return res ;
14   }
15 }