题解 | 2025/7/30（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 the head node
     * @return ListNode类
     */
    public ListNode sortInList (ListNode head) {
        // write code here
        if (head == null || head.next == null) {
            return head;
        }
        // 寻找中心节点
        ListNode slow = head;
        for (ListNode fast = head; fast.next != null && fast.next.next != null; fast = fast.next.next) {
            slow = slow.next;
        }
        ListNode temp = slow.next;
        slow.next = null;

        // 递归两边
        ListNode left = sortInList(head);
        ListNode right = sortInList(temp);

        // 合并两个有序列表
        ListNode dummy = new ListNode(0);
        ListNode cur = dummy;
        while (left != null && right != null) {
            if (left.val <= right.val) {
                cur.next = left;
                left = left.next;
            } else {
                cur.next = right;
                right = right.next;
            }
            cur = cur.next;
        }
        cur.next = left == null ? right : left;
        return dummy.next;
    }
}