Find Min Sum
Reported by candidates from TikTok's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
TikTok's February OA included a problem called Find Min Sum, and you're likely seeing it 24-48 hours before you sit down. The problem title is minimal, which means the actual task could pivot on a single constraint or input twist. Without the verbatim text, you're looking at a greedy or dynamic programming play, most likely. StealthCoder will catch the pattern live if you blank on whether to sort, accumulate, or recurse.
Pattern and pitfall
Find Min Sum problems typically ask you to construct the smallest possible sum by selecting, ordering, or pairing elements from one or more arrays. The trick is almost always about whether you're sorting ascending or descending, and whether you're hitting a greedy choice first or building up a table. The most common version pairs two arrays: sort one ascending, the other descending, then multiply pairs and sum. A DP variant might ask you to select exactly k elements with minimum cost. The pitfall: assuming the greedy choice (smallest first) works without testing a counterexample. On the live OA, if you freeze on the algorithm choice, StealthCoder reads the exact constraint and feeds you the right path.
If this hits your live OA and you blank, StealthCoder solves it in seconds, invisible to the proctor.
You can drill Find Min 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 would have shipped this the night before his JPMorgan OA if he'd had it.
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TikTok reuses patterns across OAs. Built by an Amazon engineer who would have shipped this the night before his JPMorgan OA if he'd had it. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Find Min Sum FAQ
Is this a sorting problem or dynamic programming?+
If the problem says 'select k elements and minimize sum,' it's DP with memoization or a bottom-up table. If it says 'pair elements from two arrays,' it's almost always greedy plus sorting. Check the constraint count and whether order matters.
What's the most common pitfall on this one?+
Assuming greedy always works without verifying with a small test case. Sorting one array ascending and the other descending, then pairing, is the standard hedge. If that doesn't work, you likely need to try sort-both-ascending or re-examine the pairing logic.
How hard is TikTok's version compared to other OAs?+
TikTok's OAs tend to be medium difficulty and often test your ability to spot a pattern quickly. Find Min Sum is straightforward once you identify whether it's greedy or DP. If you freeze, you've got 45 minutes left. Don't panic.
What should I code first if I have 20 minutes left?+
Write the greedy solution: sort, pair, sum. It's fast to code and often correct. If time permits, add a DP skeleton. Partial credit for a working greedy approach beats nothing.
Can I solve this without reading the full problem statement?+
No. The exact wording of constraints determines the algorithm. You need to know whether you're selecting a subset, pairing all elements, or minimizing under a cost function. Read the input/output spec twice.