删除链表的倒数第N个节点

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/**  * Definition for singly-linked list.  * function ListNode(val, next) {  *     this.val = (val===undefined ? 0 : val)  *     this.next = (next===undefined ? null : next)  * }  */ /**  * @param {ListNode} head  * @param {number} n  * @return {ListNode}  */ const removeNthFromEnd = function(head, n) {     // 在头部补一个根节点 解决链表长度为1和2的特殊情况     let node = new ListNode(0, head)     let link = node, list = node     for(let i = 0; i < n; i++){         link = link.next     }     while(link && link.next){         link = link.next         list = list.next     }     list.next = list.next?.next     return node.next };