题解 | #重排链表#

1、双指针算法

import java.util.*;
public class Solution {
    public void reorderList(ListNode head) {
        if (head == null || head.next == null) return;
        List<ListNode> list = new ArrayList<>();
        ListNode cur = head;
        while (cur != null) {
            list.add(cur);
            cur = cur.next;
        }
        int l = 0, r = list.size() - 1;
        while (l < r) {
            list.get(l).next = list.get(r);
            l++;
            list.get(r).next = list.get(l);
            r--;
        }
        list.get(l).next = null;
    }
}