题解 | #反转链表#
反转链表
https://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca
import java.util.*; /* * public class ListNode { * int val; * ListNode next = null; * public ListNode(int val) { * this.val = val; * } * } */ public class Solution { /** * 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 */ public ListNode ReverseList (ListNode head) { // write code here if (head == null) { return null; } List<ListNode> array = new ArrayList<>(); ListNode p = head; while (true) { System.out.println("p: " + p.val); if (p.next == null) { array.add(p); break; } array.add(p); p = p.next; } for (ListNode node : array) { if (node.next != null) { node.next = null; } } for (int i = array.size() - 1; i > 0; i--) { array.get(i).next = array.get(i - 1); } return array.get(array.size() - 1); } }