Cet Mean Rank Count
Reported by candidates from Amazon's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Amazon's August OA hit candidates with Cet Mean Rank Count, a sorting problem disguised as a ranking puzzle. You're looking at a dataset, computing mean ranks, and counting something specific about those ranks. The trick is recognizing that you don't need to implement a full ranking algorithm from scratch. StealthCoder can spot the pattern instantly if you freeze on the live assessment, but understanding the sorting angle now means you walk in calm. The problem feels abstract until you see the data flow.
Pattern and pitfall
This is a sorting and counting problem wrapped in rank language. The core move is sorting the dataset by the relevant metric, then computing mean ranks for grouped elements, then counting how many groups or elements hit a threshold. Common trap: trying to hand-code a ranking system instead of sorting first. You'll iterate over sorted data, assign ranks or compute means, then apply a counting filter. The 'cet' phrasing suggests a cutoff or threshold condition. StealthCoder will parse the exact counting condition from the problem statement and output the sort order plus the final loop in seconds if you blank during the OA.
If this hits your live OA and you blank, StealthCoder solves it in seconds, invisible to the proctor.
You can drill Cet Mean Rank Count cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Built by an Amazon engineer who would have shipped this the night before his JPMorgan OA if he'd had it.
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Cet Mean Rank Count FAQ
Is this really just a sort plus a count loop?+
Yes. Sort by the metric in the problem, compute mean ranks for each group or element, then count how many meet the criteria. No complex data structures needed. The confusion comes from the rank language, not the algorithm.
How do I know what to sort by if the problem is vague?+
Read carefully for the metric mentioned first. Amazon OAs typically sort by value, frequency, or a given attribute. The mean rank calculation itself tells you what dimension matters. Test a small example by hand if unsure.
What's the time complexity Amazon expects?+
O(n log n) for sorting plus O(n) for the count pass. No exotic data structures. If your solution is longer than 30 lines, you're overcomplicating it.
Do I need to handle ties in ranking?+
Probably. Ties get the same rank, and the mean rank for a tied group is the average of the rank positions they'd occupy. This is standard ranking logic. Check if the problem says 'standard' or 'dense' ranking.
Should I write this in Python or Java?+
Whatever you're fastest in. Sort is a library call. The logic is identical. Python's sorted() with a lambda key is cleaner if you know it. Don't switch languages mid-OA.