Frequently asked questions

Submit a single source file with the exact same name as the problem. For example, if the problem is called FizzBuzz, submit a file named FizzBuzz.java (Java), FizzBuzz.py (Python), or FizzBuzz.js (JavaScript) depending on the language your instructor specified. The name must match exactly — capitalization matters.

Yes, you can resubmit as many times as you like before the deadline. Your best score across all submissions is what counts toward your grade. There is no penalty for resubmitting.

Files must be 64 KB or smaller. In practice, a well-written solution to any class problem will be far below this limit. If you're hitting the limit, you likely have something unexpected in your file.

Just resubmit the correct file. The new submission replaces nothing — your old submissions stay in history — but your best score is always what counts, so a correct resubmission will update your grade.

Make sure you're signing in with your school Google account, not a personal Gmail. If you've signed into the wrong account, click "Sign in with Google" again and switch accounts in the Google login window. If the problem persists, contact your instructor.

Most submissions are graded within 15–30 seconds. The status updates automatically — you don't need to refresh the page. If a submission stays in pending or running for more than 2 minutes, let your instructor know.

Your program ran successfully but produced output that didn't match the expected output for that test case. Click View on your submission to see the side-by-side comparison of what was expected versus what your program printed. Common causes:

• Extra or missing spaces, blank lines, or punctuation
• Wrong capitalization
• Off-by-one errors (printing one too many or too few items)
• Debug System.out.println statements left in your code

Your program compiled (for Java) but crashed while running. The error details panel shows the exception message to help you debug. Common causes:

• ArrayIndexOutOfBoundsException — accessing an index that doesn't exist
• NullPointerException — using an object that was never initialized
• NumberFormatException — trying to parse a non-numeric string as a number
• StackOverflowError — infinite recursion

The autograder compares your output exactly to the expected output. Small differences your eyes skip over will cause a failure. Things to check:

• Are you printing a trailing space or extra blank line?
• Are you reading from System.in (stdin) correctly — the grader pipes the input in automatically
• Are you leaving any debug print statements in?
• Does your program exit cleanly, or does it wait for more input?

Some problems restrict certain language features — for example, a problem designed to practice for loops might disallow while, or a problem might disallow built-in sorting methods. If your submission is rejected because of a disallowed keyword, remove that construct and find another approach. Your instructor will tell you what constraints apply.

Each problem has a set number of test cases and a point value. Your score is:

(test cases passed ÷ total test cases) × problem points

For example, if a 10-point problem has 5 test cases and you pass 4, you earn 8 points. Your overall course grade on the My Grades page is your total points earned across all problems divided by the total possible points.

Submissions normally complete within 30 seconds. If yours has been stuck for more than 2 minutes, try refreshing the page. If the problem persists, note your submission ID (visible in your submission history) and contact your instructor.

The maximum file size is 64 KB. Make sure you're submitting just your .java (or .py / .js) source file, not a compiled .class file, a zip archive, or any other file type.

For Java submissions, your code didn't compile. This means there are syntax errors — missing semicolons, unmatched braces, misspelled keywords, etc. The error details panel shows the compiler output. Fix the errors in your editor, confirm the code compiles locally with javac YourFile.java, then resubmit.

Try a hard refresh (Ctrl+Shift+R on Windows/Linux, Cmd+Shift+R on Mac) to clear any cached files. If that doesn't help, submit a ticket describing what you see and which page you were on.

Your teacher will share an 8-character join code (something like ABC12XYZ). On the submit page, look for the "Join a class" prompt at the top — type the code and click Join. Once joined, your class's problems appear in the dropdown.

Yes. You can be enrolled in multiple classes (your regular CS class, plus the per-language Practice classes for example). Problems from every class you're in appear in the dropdown, grouped by class.

Most likely you haven't joined a class yet — the page shows a "Join a class to see assignments" banner when that's the case. If your teacher told you you're enrolled but problems still aren't showing, it might be that your class has problems without test cases configured yet (those are hidden from students until at least one case is uploaded). Ask your instructor to check.

Each student starts with 5 late tokens. Each token covers 24 hours past a problem's due date. If you submit late and you have enough tokens to cover how late you are, the system automatically spends those tokens and treats your submission as on-time. If you don't have enough, the submission is accepted but flagged as late.

Automatically, on submit. If you're 30 hours past the deadline, that takes 2 tokens (rounded up to whole 24-hour chunks). Submitting 49 hours late takes 3 tokens. Tokens are spent only if you have enough to fully cover the lateness — partial coverage doesn't apply, you'd just be marked late.

On the submit page, just under the problem description: "Late tokens remaining: X / 5". Hover for the explanation. The number updates the moment you submit something that consumes tokens.

Yes. Instructors can grant tokens (+1, +5, or any amount) or reset your balance back to 5 from their dashboard. Talk to them if you've run out and have a legitimate reason for an extension.

Tokens are refunded when our file-upload step fails before the submission is even queued. If your code itself errors during grading, the tokens stay spent — that's not a server issue, the system tried.

Practice problems are extra exercises grouped by language (Java, Python, JavaScript) that don't count toward your class grade. They're for sharpening skills and building confidence. Visit the Practice page to browse them.

On the Practice page, switch the language tab at the top (Java / Python / JavaScript). Each language has its own practice problems with the same names but adapted to the language's I/O conventions. To submit, you need to be enrolled in that language's practice class — your teacher can share the join code.

Those are placeholder cards for problems that aren't uploaded yet — you can see what's coming but can't submit. The clickable problems at the top are live and ready to attempt.

No — practice problems typically don't have due dates, so there's nothing for tokens to cover. Your token balance is shared across all classes, but practice submissions don't consume them.

Your instructor can manually override a grade — for example, awarding partial credit beyond what the test cases caught. When this happens you'll see a "Manually adjusted" badge on your submission and the displayed score reflects the override. The instructor's reason is stored in the audit log.

Lines starting with - are what was expected; lines starting with + are what your code actually printed. Lines without a prefix matched. The diff is collapsed by default; click Show diff on a wrong-output case to expand it.

Yes. After grading completes, scroll past the per-case results to find a comment thread. Type a message and click Send. You can also tag a comment to a specific test case using the dropdown next to the input — useful for asking about case 3 specifically without ambiguity.

Yes — every submission detail view has a Download source link that gives you back the exact file you uploaded. Useful if you didn't keep a local copy.

That's how many times you've submitted to this specific problem — your third attempt at FizzBuzz, for instance. The number is per-problem, not per-class, so submitting to a different problem starts at #1 again.