题解 | #删除有序链表中重复的元素-I#

每一次循环，都是剔除或者推进任意一步

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        // write code here
        // 循环；非空替换
        if (head == null) {
            return null;
        }
        ListNode n = head;
        ListNode pre = head, node = head.next;
        while (node != null) {
            if (pre.val == node.val) {
                pre.next = node.next;
                node = pre.next;
            } else {
                // 推进
                pre = pre.next;
                node = pre.next;
            }
        }
        return n;
    }
}