1、利用优先队列
import java.util.*;
/*
* public class ListNode {
* int val;
* ListNode next = null;
* }
*/
public class Solution {
/**
*
* @param head ListNode类
* @return ListNode类
*/
public ListNode sortList (ListNode head) {
// write code here
if (head == null || head.next == null) return head;
Queue<ListNode> queue = new PriorityQueue<>((a, b) -> a.val - b.val);
ListNode cur = head;
while (cur != null) {
queue.offer(cur);
cur = cur.next;
}
ListNode dummy = new ListNode(0);
cur = dummy;
while (!queue.isEmpty()) {
cur.next = queue.poll();
cur = cur.next;
}
cur.next = null;
return dummy.next;
}
}