[LeetCode] 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.

[Solution].java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(head == null) return null;
        
        ListNode left = head;
        int val = left.val;
        ListNode right = head.next;
        while(right != null){
            if(right.val == val) right = right.next;
            else{
                left.next = right;
                left = right;
                val = left.val;
                right = right.next;
            }
        }
        left.next = right;
        return head;
    }
}