题解 | #反转链表#

/*
 * function ListNode(x){
 *   this.val = x;
 *   this.next = null;
 * }
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
function ReverseList( head ) {
    // write code here
    let arr = []
    if(!head){return head}
    let bianli = function bianli(root){
        root.val && arr.push(root.val);
        root.next && bianli(root.next);
    }
    let reverse = function reverse(root,index){
        root.val && (root.val = arr[index]);
        root.next && reverse(root.next,index+1);
    }
    bianli(head);
    arr.reverse();
    reverse(head,0);
    return head

}
module.exports = {
    ReverseList : ReverseList
};