Sort Product Codes
Reported by candidates from Amazon's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Amazon's February OA included a straightforward sorting problem: arrange product codes in a specific order. The trap is assuming the order is lexicographic or numeric when it's actually custom. You need to read the sorting criteria carefully, implement the comparator correctly, and handle edge cases like duplicate codes or mixed alphanumeric strings. This is a sorting fundamentals check, and if you blank on the comparator syntax during the live OA, StealthCoder reads the problem aloud and hands you the pattern in seconds.
Pattern and pitfall
The core pattern is custom comparator implementation. Amazon isn't testing if you know sort() exists, but whether you can define the sort order when it's not alphabetical or numerical. The gotcha: candidates often hardcode the wrong sort key or misread whether the order is ascending or descending. The approach is to parse the sorting rule from the problem statement, implement a comparator function that reflects that rule, and apply it to your sort call. Pitfall: forgetting that some product codes may contain letters and numbers mixed, requiring careful parsing logic. This is where StealthCoder's real-time problem re-read becomes your safety net if you misunderstood the rule on first pass.
The honest play: practice the pattern, and have StealthCoder ready for the one you didn't see coming.
You can drill Sort Product Codes 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 for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play.
Get StealthCoderRelated leaked OAs
This OA pattern shows up on LeetCode as custom sort string. If you have time before the OA, drill that.
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Amazon reuses patterns across OAs. Built for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Sort Product Codes FAQ
What if the sorting rule involves multiple criteria, like primary sort by code type then by code value?+
Chain your comparator conditions. Check the primary criterion first, and if it's equal, move to the secondary. Most Amazon sorting problems use 2-3 criteria. Read the problem twice to make sure you catch all of them.
Is this problem asking for a stable sort or does order not matter for equal elements?+
The problem statement will clarify. If it doesn't explicitly say, assume stable sort (preserve original order for ties). Most languages' built-in sort is stable, so use that unless told otherwise.
How do I handle alphanumeric product codes without overthinking it?+
Don't. Use the built-in string comparison first, then adjust only if the problem explicitly requires a different order. Alphanumeric sorting in most languages compares character-by-character lexicographically, which is often correct.
What's the time complexity I should aim for?+
Standard sort is O(n log n). If the problem expects faster, it'd hint at it. For 10000 product codes, O(n log n) is fine. Focus on correctness first, optimization only if the problem mentions performance.
Should I write my own sort or use the built-in library?+
Always use the built-in sort with a custom comparator. Writing your own quicksort or merge sort in an OA wastes time and introduces bugs. The problem is testing your ability to define the sort order, not implement sorting from scratch.