Define and implement the judge verdict

[akamya997]

Since we have completed the basic work flow of judger, we should define the judge verdict for further development and test.

There are two key tasks to do:

• Define the judge verdict (like Accept, TLE, RE, etc.)
• In monitor.rs, the run_judge and run_interact function is expected to return the verdict directly, as well as some other status of the user program (or is there a better design?). A simplest way to implement it is to check the result from sandbox.

I want to discuss more details on it, like how to decide the verdict for TLE, and what kind of status should be returned.

[akamya997]

For now, a simple test case is run in run_judge. We define the judge verdict as following:

pub enum JudgeVerdict {
    Accepted,
    WrongAnswer,
    TimeLimitExceeded,
    IdlenessLimitExceeded,
    RuntimeError,
    PartialScore,
    SystemError,
}

And the function run_judge return the result information as following:

pub struct JudgeResultInfo {
    pub verdict: JudgeVerdict,
    pub time: i64,
    pub memory: i64,
    pub exit_status: i32,
    pub checker_exit_status: i32,
}

We simply use the exit status to decide the judging result.
If the checker can run successfully, we check the checker's output to decide AC/WA.