题解 | #反转链表#

function ListNode(x){
    this.val = x;
    this.next = null;
}
function ReverseList(Head)
{
    if(!Head) {
       let node = new ListNode(null);
        return null
    }
    if (Head.next == null) return Head;//只有一个节点的情况
    if(Head.next.next == null){  //找到倒数第二个节点
        Head.next.next = Head;
        return Head.next //返回新的根节点
    }
    let result = ReverseList(Head.next);
    Head.next.next = Head;
    Head.next = null; //防止出现闭环
    return result
}
module.exports = {
    ReverseList : ReverseList
};