优先队列偷懒

优先队列里放节点，然后一个一个取出来接到新链表后边(这样也算是交换节点而不是修改值，不过有一个坑需要注意，大家可以评论区说说哈哈哈)

```import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param head ListNode类 the head node
     * @return ListNode类
     */
    public ListNode sortInList (ListNode head) {
        // write code here
        PriorityQueue<ListNode> priorityQueue = new PriorityQueue<>((l1,l2) -> l1.val-l2.val);
        ListNode pre = head;
        while (pre!=null) {
            priorityQueue.offer(pre);
            pre = pre.next;
        }
        ListNode res = new ListNode(0);
        ListNode curr = res;
        while (!priorityQueue.isEmpty()) {
            curr.next = priorityQueue.poll();
            curr = curr.next;
        }
        curr.next = null;
        return res.next;
    }
}