struct ListNode* insertionSortList(struct ListNode* head){
     if(head == NULL||head->next == NULL)
        return head;
        //初始条件
    struct ListNode* sortHead = head;
    struct ListNode* cur = head->next;
    sortHead->next = NULL;
    while(cur)//终止条件
    {
        //迭代条件
        struct ListNode* next = cur->next;
        //将cur节点插入到前面有序区间
        struct ListNode* p = NULL,*c = sortHead;
        while(c)
        {
            if(cur->val < c->val)
            {
                break;
            }
            else
            {
                p = c;
                c = c->next;
            }     
        }
        if(p == NULL)
        {
            cur->next = c;
            sortHead = cur;
        }
        else
        {
            p->next = cur;
            cur->next = c;
        }
        cur = next;
    }
    return sortHead;
}