Return the number of nodes in the linked list.
Examples
L = null, return 0
L = 1 -> null, return 1
L = 1 -> 2 -> null, return 2
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 }