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No AI eyeballing your code and guessing. Every submission below runs for real, in a sandbox, against the exact test cases Phantom Learn uses — try it right now, no signup.
Write sumTable(tbl) so it returns the sum of every number in tbl.
Tested against 4 fixed cases plus 3 freshly randomized ones — generated new, every run.
Why it's built this way
Grading by vibes doesn't teach you anything. Every one of these is a real, load-bearing part of how Phantom Learn decides if your code actually works.
Your code runs with hard memory, CPU, and process caps. An infinite loop or a memory bomb gets killed cleanly and just fails that case — it can't take anything else down with it.
Test inputs aren't fixed. A fresh set generates each time you submit, so copying a known-good answer for one input doesn't help you pass the next.
Output is checked against the real expected value, case by case. Not "looks about right" — matches, or it doesn't.
Roadmap