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.

Use two pointers

/**
 * 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) {
        if(head == null || head.next == null) return head;
        ListNode h = head;
        ListNode p = head;
        ListNode q = head.next;
        while(q != null){
            if(q.val == p.val){
                p.next = q.next;
            }else{
                p.next = q;
                p = p.next;
            }
            q = q.next;
        }

        return h;
    }
}