LeetCode77|排序链表

示例 1:

输入: 4->2->1->3
输出: 1->2->3->4
示例 2:

输入: -1->5->3->4->0
输出: -1->0->3->4->5

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class SortListTest2 {
    public static void main(String[] args) {
        ListNode l1 = new ListNode(4);
        ListNode l2 = new ListNode(2);
        ListNode l3 = new ListNode(1);
        ListNode l4 = new ListNode(3);
        l1.next = l2;
        l2.next = l3;
        l3.next = l4;
        ListNode listNode = sortList(l1);
        System.out.println("listNode = " + listNode);

    }

    public static ListNode sortList(ListNode head) {
        if (head == null || head.next == null) {
            return head;
        }
        List<Integer> list = new ArrayList<>();
        ListNode temp = head;
        while (temp != null) {
            list.add(temp.val);
            temp = temp.next;
        }
        Collections.sort(list);
        ListNode dummyNode = new ListNode(-1);
        ListNode tempNode = dummyNode;
        for (Integer integer : list) {
            tempNode.next = new ListNode(integer);
            tempNode = tempNode.next;
        }
        return dummyNode.next;
    }
}