147. Insertion Sort List

题目：

Sort a linked list using insertion sort.

对链表进行插入排序。

public ListNode insertionSortList(ListNode head) {  if(head == null || head.next == null) return head;ListNode newnode =new ListNode(0);newnode.next = head;ListNode p = head.next;head.next=null;ListNode cur;while (p!=null){cur =p;p=p.next;ListNode node=newnode.next; //已排好序头节点ListNode pre = newnode;while(true){if(cur.val<node.val) //将cur节点插入到node前面{pre.next = cur;cur.next= node;break;}else{   //node后移pre = node;node=node.next;}if(node ==null)  //将cur添加到已排好序最后{pre.next=cur;cur.next=null;break;}}}return newnode.next;}