FTPrep, 83 Remove Duplicates from Sorted List

值得总结的就是：与array相比，要修改（在list中是断开链接操作）一个值，没有index所以不具备array的功能。

所以只能通过node的前续节点来access/getter 并且比较，然后再做断开修改的方式.

一般只要断开的，都是通过前继节点，比如说remove the last k-th node的那道题。TODO，值得总结，list的各种处理方式

代码：

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */class Solution {    public ListNode deleteDuplicates(ListNode head) {        if(head==null) return head;        ListNode dummy = new ListNode(-1);        dummy.next=head;        ListNode checkValidForNext=dummy;        ListNode scanCurrAndCompareNext=head;        while(scanCurrAndCompareNext!=null){            while(scanCurrAndCompareNext.next!=null && checkValidForNext.next.val==scanCurrAndCompareNext.next.val) {                scanCurrAndCompareNext=scanCurrAndCompareNext.next;               }            checkValidForNext.next =scanCurrAndCompareNext; // nice, directly link to the last one in any duplicate series.            checkValidForNext=checkValidForNext.next; // move 1 step so points to the valid node, and ready to check the next one            scanCurrAndCompareNext=scanCurrAndCompareNext.next; // move 1 step for scan pointer too.        }        return dummy.next;    }}// 值得总结的就是：与array相比，要修改（在list中是断开链接操作）一个值，没有index所以不具备array的功能。// 所以只能通过node的前续节点来access/getter 并且比较，然后再做断开修改的方式.// 一般只要断开的，都是通过前继节点，比如说remove the last k-th node的那道题。TODO，值得总结，list的各种处理方式