Reading a verdict

What to read first

Find the first stage that did not pass. Read its message and the example, if one is shown. Compare the expected answer with your answer. Fix one thing, then run a quick check again.

Result names

Result	Meaning	Next step
`PASS`	All checks up to your target passed.	Try the next stage.
`FAIL`	A check failed.	Read the message and fix the behavior.
`FLAKY`	Some runs passed and others failed.	Look for a race. Read Many callers at once.
`DID NOT BUILD`	Your code did not build.	Read the compiler output.
`CRASHED`	Your program stopped with an error.	Read the error and stack trace.
`TIMED OUT`	Your program took too long.	Look for a stuck loop or a long wait.
`UNREADABLE OUTPUT`	The tester could not read your program's output.	Check the required return types. Send debug messages to stderr.
`NOT GRADED HERE`	This stage did not run.	Read the reason shown.
`GRADER PROBLEM`	Our service could not finish the check.	This is not your fault. We retry automatically.

When the result is FLAKY

Each stage runs a few times. FLAKY means your code passed sometimes and failed other times. That is what a race looks like: many callers reach your code at once, and the answer depends on which one gets there first. Running the check again and hoping for a pass does not fix it. Look for a place where your code reads a value, decides, and then writes it back. Many callers at once explains the bug and how a lock fixes it.

When correct code is too slow

L2 compares your speed with a working solution in the same language. Correct answers alone are not enough for this level. Look for repeated scans, copying, or new memory created on every call. The results show how fast your code was. Memory counts are shown for information only.

Get help

Open the challenge's Notes tab for a short introduction and a wiki link. Use faultline notes <challenge> for the same help from the command line. Use --full to read the whole page. If a problem continues, send us the submission id.