Apply Operations to Make Sum of Array Greater Than or Equal to k
A medium-tier problem at 43% community acceptance, tagged with Math, Greedy, Enumeration. Reported in interviews at ZScaler and 1 others.
You've got an array and k, and you need to make the sum hit a target by applying operations. ZScaler and Turing have both asked this. It looks simple on the surface, but the trick isn't obvious until you've done it wrong once. The greedy strategy most people jump to fails because they don't enumerate the right operation sequence. If you hit this live and blank on the pattern, StealthCoder pulls a working solution in seconds, invisible to the proctor. With a 43% acceptance rate, this problem separates people who understand the greedy insight from those who brute-force or overcomplicate.
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Apply Operations to Make Sum of Array Greater Than or Equal to k 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe core insight is that you need to pick the right operation sequence to maximize the array sum with minimal moves. Most candidates start by greedily doubling the smallest element every time, but that's suboptimal because you might waste operations early. The real pattern: enumerate different operation counts and compute the best sum you can achieve with exactly that many operations. For each operation count, the optimal move is always to double the smallest element at that step. This shifts from 'which operation should I do first' to 'how many total operations do I need, and what's the best sum I can achieve with that budget.' The greedy core survives, but the enumeration wrapper changes everything. StealthCoder handles the enumeration logic and the greedy inner loop in real time if you freeze during the live assessment.
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Apply Operations to Make Sum of Array Greater Than or Equal to k 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Apply Operations to Make Sum of Array Greater Than or Equal to k interview FAQ
Why doesn't greedy 'always double the smallest' work without enumeration?+
Greedy alone doesn't minimize operations. You might double a large element early when you should double the smallest element later. Enumeration forces you to test all possible operation counts and pick the one that reaches k with the fewest moves. The greedy strategy applies within each enumeration candidate, not across all choices.
Is this problem still asked at tech companies?+
Yes. ZScaler and Turing both report it. At 43% acceptance, it's harder than leetcode's easy-medium average, which keeps it relevant for real interviews. It tests both greedy thinking and the ability to recognize when enumeration is necessary.
What's the main pitfall candidates hit?+
Assuming one greedy strategy is always best. Candidates often code 'always double the smallest' and never check other operation counts. The problem wants the minimum number of operations to reach k, so you must test multiple budgets and pick the one that works first.
How does Math and Enumeration interact here?+
Math covers the doubling and sum calculations. Enumeration is the outer loop testing operation counts from 0 to some upper bound. You combine both: enumerate operation budgets, then use math and greedy logic to compute the best sum for each budget.
What's a reasonable upper bound for operations to enumerate?+
If you double the smallest element repeatedly, the sum grows exponentially. Enumerate up to roughly log2(k / initial_sum) as a starting heuristic, then adjust if needed. The exact bound depends on the input, but enumeration stops being useful once the sum clearly exceeds k.
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