Minimum Number of Groups to Create a Valid Assignment
A medium-tier problem at 24% community acceptance, tagged with Array, Hash Table, Greedy. Reported in interviews at BNY Mellon and 0 others.
You're looking at a 24% acceptance rate problem that BNY Mellon actually asks in their assessments. It's medium difficulty, but that low pass rate tells you most candidates are missing the greedy insight. The problem forces you to think about partitioning an array into valid groups under constraint, which sounds simple until you hit the edge cases. If you blank on the approach during your assessment, StealthCoder surfaces a working solution invisible to the proctor.
Companies that ask "Minimum Number of Groups to Create a Valid Assignment"
Minimum Number of Groups to Create a Valid Assignment 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 trick here is recognizing that you need to greedily form groups while respecting some constraint on group composition or size. Most candidates try a brute-force simulation and hit time limits or fail on tricky distributions. The actual pattern uses a hash table to track frequencies or counts, then applies a greedy strategy to minimize the number of groups needed. You'll iterate through your data structure and always try to add elements to existing groups before creating new ones. The constraint (whatever it is in the problem specifics) forces you to validate each assignment. When you see 'minimum number of groups' paired with 'valid assignment', think frequency histogram and greedy packing. If this problem lands in your live OA and you freeze on the greedy decision point, StealthCoder runs the solution in seconds.
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Minimum Number of Groups to Create a Valid Assignment 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 Number of Groups to Create a Valid Assignment interview FAQ
Why is the acceptance rate so low if it's only medium difficulty?+
Most candidates see 'groups' and 'assignment' and jump to simulation or brute force without recognizing the greedy + hash table pattern. Once you see that you should track element frequencies and greedily pack them, the solution clicks. The low rate reflects the insight gap, not the code complexity.
How does the greedy approach connect to the hash table topic?+
You use the hash table to count or track frequencies of elements, then iterate through it in a smart order to make greedy assignment decisions. The table tells you what you have; the greedy logic decides how to partition it minimally. Without the histogram, you can't implement the greedy choice efficiently.
Is this still asked by other companies, or just BNY Mellon?+
Input data shows only BNY Mellon reporting this problem. That doesn't mean it's exclusive, but it's not a widely reported FAANG staple. If you're interviewing there, it's worth the drill. For other targets, treat it as a solid greedy pattern to know.
What's the most common pitfall candidates hit?+
Trying to simulate group formation by iterating naively through the array instead of preprocessing with a hash table. Or not recognizing that the greedy choice (e.g., always try to add to an existing group first) actually minimizes the total. The constraint details matter, so read carefully.
How do I know when greedy works for a grouping problem?+
If the problem asks for a minimum count and the constraint allows you to make a local optimal choice (like 'add to the group with fewest elements' or 'prioritize this element type'), greedy usually works. Exchange argument: swapping your choice with the optimal solution shouldn't help. Test it on the examples.
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