Counter
A easy-tier problem at 82% community acceptance, tagged with . Reported in interviews at CARS24 and 0 others.
Counter is an easy problem that CARS24 has asked, sitting at an 82% acceptance rate. Sounds like a gimme until you realize the assessment environment is unfamiliar, your nerves are high, and you blank on the exact method call or loop syntax. This is the kind of problem where you don't fail on algorithm, you fail on execution under pressure. If you hit it live and freeze, StealthCoder surfaces a working solution in seconds while the proctor sees nothing but your typing.
Companies that ask "Counter"
Counter is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderCounter problems typically require you to track frequency or occurrence of elements, then output results in a specific order. The trap isn't the logic, it's the implementation details: choosing the right data structure (hash map, array, or built-in counter), iterating correctly, and handling edge cases like ties or sorting order. Most candidates know what to do in theory but stumble on syntax, iteration order, or forgetting to actually return the result in the right format. Since this is easy-tier at CARS24, the real risk is careless mistakes that cost you time you can't afford to lose. StealthCoder is the safety net if the live OA throws you off your rhythm on a problem you thought you knew.
You know the problem.
Make sure you actually pass it.
Counter recycles across companies for a reason. It's easy-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Counter interview FAQ
Is Counter still asked at CARS24?+
Yes. It's in their reported interview pool. At 82% acceptance, it's a high-bar problem for them, lots of candidates pass it. That means it's also the kind of problem you can't afford to stumble on, because most people don't.
What's the actual trick to Counter?+
There usually isn't one. You count occurrences with a hash map or array, then either sort, filter, or return results in a specific order. The trick is avoiding off-by-one errors, handling ties correctly, and matching the output format exactly. Read the problem statement carefully for sort order.
How do I know which data structure to use?+
If you need frequency counts, a hash map (dictionary) or built-in Counter object is standard. If the input range is small and known, an array works too. Your language's standard library almost always has a ready-made solution. Use it instead of building from scratch.
What's the most common mistake on easy problems like this?+
Not reading the output format carefully. You count correctly but return the wrong structure, or forget to sort, or sort ascending instead of descending. Also common: assuming the input is clean when it might have duplicates or edge cases you didn't test for.
How long should Counter take me in a real assessment?+
If you know your language's standard library, 5 to 10 minutes. If you're writing a hash map from scratch or second-guessing your approach, you'll burn 15-20. Easy problems shouldn't be your time sink. If you're stuck, move on and come back.
Want the actual problem statement? View "Counter" on LeetCode →