将一个单链表进行处理后，所得结果为一有序链表
Solution:
将原始链表逐个查询，插入新链表，在插入的同时对链表进行排序。时间复杂度O(n*n)
public ListNode insertionSortList(ListNode head) { ListNode dummy = new ListNode(0); while (head != null) { ListNode node = dummy; while (node.next != null && node.next.val < head.val) { node = node.next; } ListNode temp = head.next; head.next = node.next; node.next = head; head = temp; } return dummy.next; }