- fix original logic issue of cases generation (originally there is duplication on cases, e.g. `case5`, `task1/case5`)
- fix the issue that without any specification there is no cases input and output in `diff` stage
Co-authored-by: Boming Zhang <bomingzh@sjtu.edu.cn>
Reviewed-on: #14
Reviewed-by: 张泊明518370910136 <bomingzh@sjtu.edu.cn>
Co-authored-by: jon-lee <jon-lee@sjtu.edu.cn>
Co-committed-by: jon-lee <jon-lee@sjtu.edu.cn>
