Remove Duplicates from Sorted List

RemoveDuplicatesFromSortedList.java

/**
 * 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) {
        /*
        1 2 3 3 3 4 !=
        ^ ^
        1 2 3 3 3 4 !=
          ^ ^
        1 2 3 3 3 4 ==
            ^ ^
        1 2 3 3 3 4 ==
            ^   ^
        1 2 3 3 3 4 !=
            ^     ^
        */
        if (head == null)
            return null;
        
        ListNode last = head, cur = head.next;
        while (cur != null) {
            if (cur.val == last.val) {
                cur = cur.next;
            } else {
                last.next = cur;
                last = cur;
                cur = cur.next;
            }
        }
        last.next = null;
        return head;
    }
}