83. Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.


/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        
        ListNode check = head;
        //nested while loop
        while (check !=null){
           while (check.next !=null && check.val == check.next.val){ 
                check.next= check.next.next; // skip the next node
                
            }
            
            check = check.next; // move to next node
        }
        
        return head;
        
    }
}