题解 | 单链表的排序

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
        //思路分析：直接将链表节点放到ArrayList中，自定义排序规则即可
        ArrayList<Integer> list = new ArrayList<>();
        while(head != null){
            list.add(head.val);
            head = head.next;
        }

        list.sort(new Comparator<Integer>(){
            @Override
            public int compare(Integer i,Integer j){
                return i - j;
            }
        });

        //3.新节点 + 新链表
        ListNode dummyNode = new ListNode(-1);//虚拟节点
        ListNode cur = dummyNode;
        for (int i = 0; i < list.size(); i++) {
            cur.next = new ListNode(list.get(i));
            cur = cur.next;
        }
        return dummyNode.next;
    }
}