fix typo ；创建不存在的文件夹 ；加强有效性判断
fix typo ；创建不存在的文件夹 ；加强有效性判断

uestcxl/OnlineJudge,wwj718/OnlineJudge,wangmingjob/OnlineJudge,hxsf/OnlineJudge,Timeship/OnlineJudge-1,Timeship/OnlineJudge-1,hxsf/OnlineJudge,wangmingjob/OnlineJudge,hxsf/OnlineJudge,Timeship/OnlineJudge-QDU,Timeship/OnlineJudge-1,wangmingjob/OnlineJudge,wwj718/OnlineJudge,Timeship/OnlineJudge-QDU,Timeship/OnlineJudge-1,Timeship/OnlineJudge-QDU,wwj718/OnlineJudge,uestcxl/OnlineJudge,Timeship/OnlineJudge-QDU,hxsf/OnlineJudge,wangmingjob/OnlineJudge,uestcxl/OnlineJudge