Get Max Skill Sum
Reported by candidates from Amazon's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Amazon's December OA threw this one at candidates: Get Max Skill Sum. No problem text leaked, but the title tells you everything. You're maximizing a sum across skills, which means you're either picking a subset, ordering things, or using dynamic programming to avoid a greedy trap. If you blank on the pattern during the live OA, StealthCoder reads the full problem and gives you the approach in seconds. The real candidates who reported this one had 60-90 minutes, no retakes.
Pattern and pitfall
Max sum problems at Amazon usually hide a constraint. It's rarely just "pick the biggest numbers." Watch for: skill dependencies (you need skill A before B), a cost or cooldown between selections, or a limited resource pool. The pattern is either greedy with a trick, DP with state compression, or recognizing that you're actually sorting and taking a prefix. Common pitfall: assuming order doesn't matter when it does. During the live assessment, if you can't immediately see whether greedy works, you need the full problem statement fast. That's where StealthCoder comes in as your safety net, parsing the exact constraints and showing you the DP recurrence or the sorting key you missed.
If you see this problem in your OA tomorrow, the play is to recognize the pattern in 30 seconds. StealthCoder buys you that recognition.
You can drill Get Max Skill Sum 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 passed his OA cold and still thinks the filter is broken.
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Amazon reuses patterns across OAs. Built by an Amazon engineer who passed his OA cold and still thinks the filter is broken. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Get Max Skill Sum FAQ
Is this a pure DP problem or can greedy work?+
Depends on constraints you won't see until the OA. If skills have dependencies or a cost, it's DP. If it's truly independent selections, greedy (sort and take top K) works. Read the problem carefully. Greedy trap is real here.
What if there's a constraint on how many skills I can pick?+
Then you're doing a bounded knapsack or selection problem. Sort by some metric (skill value, efficiency ratio), then greedily pick the top K items. Efficiency = value per cost or similar. Check what metric matters.
How hard is this compared to other Amazon OA questions?+
Medium-hard. The title is vague, so the real difficulty is parsing the hidden constraint. Once you see it, the solution is usually 15-20 lines of code. Don't overthink unless dependencies are explicitly stated.
Should I code a brute force first or jump to DP?+
Code brute force first if you have 45+ minutes left. If you're 10 minutes in and don't see the pattern, brute force (try all subsets) buys you partial credit and forces you to understand the problem.
What's the most common mistake candidates make on this one?+
Forgetting that skills might have a prerequisite or ordering constraint. They code the greedy solution, it fails on test 3, and they run out of time. Read the problem statement twice before coding.