简单的插入排序，总是超时，暂且放在这记录一下。

class Solution:
    # @param head, a ListNode
    # @return a ListNode
    def insertionSortList(self, head):

		if head == None or head.next == None:
			return head
		psuhead = ListNode(-1)
		while head:
			tail = psuhead
			headnext = head.next
			while tail.next and tail.next.val < head.val:
				tail = tail.next
			head.next = tail.next
			tail.next = head
			head = headnext
		return psuhead.next

ListNode *insertionSortList(ListNode *head) {
	if(head == NULL || head->next == NULL)
		return head;
	//排序涉及到头结点的变化，为了方便，我们定义一个额外的伪头结点
	ListNode *psuHead = new ListNode(-1);
	while(head){
		ListNode *pre = psuHead;
		ListNode *tail = psuHead->next;
		while(tail && tail->val < head->val){
			pre = tail;
			tail = tail->next;
		}
		ListNode *nextHead = head->next;
		head->next = pre->next;
		pre->next = head;
		head = nextHead;
	}

	head = psuHead->next;
	delete (psuHead);
	return head;
}