LeetCode - Remove Duplicates from Sorted List

    Description：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.

                      给一个有序链表，删除重复的元素。还是首先考虑head == null的情况。

        

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