题解 | #反转链表#

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head == null){
            return null;
        }
        if(head.next == null){
            return head;
        }
        ListNode last = ReverseList(head.next);
        head.next.next = head;
        head.next = null;
        return last;
    }
}