题解 | #反转链表# [S-P1]

简单

public class Solution {
    public ListNode ReverseList(ListNode head) {
      if (head == null) return null;
       
      ListNode sentinal = new ListNode(-1);
      sentinal.next = head;
      while (head.next != null) {
        ListNode n = head.next;
        head.next = n.next;
        n.next = sentinal.next;
        sentinal.next = n;
      }
      return sentinal.next;
    }
}