LintCode_173 链表插入排序

ListNode *insertionSortList(ListNode *head) {
	// write your code here
	if (!head) return NULL;
	ListNode* root = head;
	head = head->next;
	root->next = NULL;
	ListNode* p;
	while (head)
	{
		p = head;
		head = head->next;
		p->next = NULL;
		ListNode* t, *ft;
		ft = t = root;
		if (root->val >= p->val)
		{
			p->next = root;
			root = p;
		}
		else
		{
			while (t && t->val < p->val)
			{
				ft = t;
				t = t->next;
			}
			if (!t) ft->next = p;
			else
			{
				ft->next = p;
				p->next = t;
			}
		}
	}
	return root;
}