前端算法-leecode-20 删除链表的倒数第N个节点

var removeNthFromEnd = function (head, n) {
    let dummy = new ListNode();
    dummy.next = head;
    let n1 = dummy; //慢
    let n2 = dummy; //快指针
    for (let i = 0; i <= n; i++) {//n2移动n+1次
        n2 = n2.next;
    }
    while (n2 !== null) {//同时移动n1，n2
        n1 = n1.next;
        n2 = n2.next;
    }
    n1.next = n1.next.next;//删除元素
    return dummy.next;
};