Minimum Moves to Make Array Complementary
A medium-tier problem at 42% community acceptance, tagged with Array, Hash Table, Prefix Sum. Reported in interviews at CureFit and 0 others.
You're given two arrays and need to find the minimum moves to make them complementary, where each pair of elements sums to the same target. CureFit has asked this problem. The acceptance rate sits at 42%, which means half the candidates who attempt it walk away empty-handed. The trick isn't about brute force iteration; it's about recognizing that you only need to check a finite set of candidate targets, then counting moves efficiently with a prefix sum. If you hit this during your OA and the greedy approach fails, StealthCoder surfaces the optimal solution in seconds, invisible to the proctor.
Companies that ask "Minimum Moves to Make Array Complementary"
Minimum Moves to Make Array Complementary 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 a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe naive approach, try every possible target sum and count moves for each, times out because the range is too large. The insight is that the optimal target must be one of a small set of candidates: the sums formed by pairs of elements in the two arrays, plus boundary sums. Once you've identified these candidates, use prefix sums and a hash table to count how many elements in each array fall outside the valid range for a given target, then pick the target with the lowest total cost. The problem rewards pattern recognition over raw computation. Most candidates fail because they don't realize the target space is bounded. If you get stuck mid-assessment, StealthCoder eliminates the guessing and runs the candidate enumeration and prefix-sum counting for you.
Pattern tags
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Minimum Moves to Make Array Complementary recycles across companies for a reason. It's medium-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 a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Minimum Moves to Make Array Complementary interview FAQ
Is this really a medium-difficulty problem?+
By the 42% acceptance rate, yes. It looks straightforward until you try brute force and timeout. The medium tier here is about spotting the bounded-target insight and implementing prefix sums correctly, not raw algorithmic complexity.
What's the main trick I'm missing if my solution times out?+
You're iterating over too many possible target sums. The key is to realize the optimal target is always a sum formed by two elements or a boundary case. Enumerate only those candidates, then use hash table and prefix sum to count moves in linear time per candidate.
How do I use prefix sums here?+
Once you fix a target sum and a valid range for elements, prefix sums let you query how many elements fall outside that range in O(1) time after O(n) preprocessing. This avoids re-counting for each element every iteration.
Why is CureFit the only company listed for this problem?+
This problem appears in very few public reports. CureFit is the one company with confirmed data. It doesn't mean others don't ask it, just that it's not widely documented in interview databases.
Can I solve this without prefix sums?+
Technically yes, but it'll be slow. Prefix sums let you count moves in O(1) per target after linear preprocessing. Without them, you're O(n) per target, and with multiple candidates, you risk timeout on larger inputs.
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