题目：

题解：

class Solution {public ListNode insertionSortList(ListNode head) {if (head == null) {return head;}ListNode dummyHead = new ListNode(0);dummyHead.next = head;ListNode lastSorted = head, curr = head.next;while (curr != null) {if (lastSorted.val <= curr.val) {lastSorted = lastSorted.next;} else {ListNode prev = dummyHead;while (prev.next.val <= curr.val) {prev = prev.next;}lastSorted.next = curr.next;curr.next = prev.next;prev.next = curr;}curr = lastSorted.next;}return dummyHead.next;}
}