82. Remove Duplicates from Sorted List II（js）

82. Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

Example 1:

Input: 1->2->3->3->4->4->5
Output: 1->2->5

Example 2:

Input: 1->1->1->2->3
Output: 2->3
题意：给定一个链表，删除所有有重复值的节点，返回这个链表
代码如下：

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var deleteDuplicates = function(head) {
    if(!head || !head.next) return head;
    let start=new ListNode(0);
    start.next=head;
    let pre=start;
    while(pre.next){
        let cur=pre.next;
        while(cur.next && cur.next.val===cur.val) cur=cur.next;
        if(cur!=pre.next) pre.next=cur.next;
        else pre=pre.next;
    }
    return start.next;
};