题解 | #牛群的身高排序#

考察链表的操作。借助于集合存储所有的值，排序之后新建链表即可完成链表的排序。

完整的Java代码如下所示

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 sortList (ListNode head) {
        // write code here
        ArrayList<Integer> arrayList = new ArrayList<>();
        while (head != null) {
            arrayList.add(head.val);
            head = head.next;
        }
        arrayList.sort(new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o1 - o2;
            }
        });
        ListNode result = new ListNode(0);
        ListNode target = result;
        for (int i = 0; i < arrayList.size(); i++) {
            result.next = new ListNode(arrayList.get(i));
            result = result.next;
        }
        return target.next;
    }

}