题解 | 2025/7/31（链表）（Java）

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 oddEvenList (ListNode head) {
        // write code here
        ListNode dummy1 = new ListNode(0);
        ListNode dummy2 = new ListNode(0);
        ListNode cur = head, cur1 = dummy1, cur2 = dummy2;
        for (int i = 1; cur != null; i ^= 1, cur = cur.next) {
            if (i == 1) {
                cur1.next = cur;
                cur1 = cur1.next;
            } else {
                cur2.next = cur;
                cur2 = cur2.next;
            }
        }
        cur2.next = null;  // 标记清空
        cur1.next = dummy2.next;
        return dummy1.next;
    }
}