Sell Diminishing-Valued Colored Balls
A medium-tier problem at 30% community acceptance, tagged with Array, Math, Binary Search. Reported in interviews at Groupon and 1 others.
You're staring at a problem where you sell colored balls at decreasing prices, and the constraint hits different. Groupon and MathWorks both ask this one. The acceptance rate sits at 30 percent because most candidates either brute-force it into a timeout or miss the greedy pattern entirely. The trick isn't sorting or binary search alone. You need to see that maximizing profit means selling the most frequent color first, then strategically alternating to avoid bottlenecking on a single color. If this problem surfaces in your OA and you blank on the sequencing strategy, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Sell Diminishing-Valued Colored Balls"
Sell Diminishing-Valued Colored Balls 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. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe core insight is greedy selection combined with priority queues. You don't just sort by frequency and sell. The real challenge: if one color dominates, you'll run out of other colors to interleave with it, and you're forced to sell it at rock-bottom prices. The optimal move is to always sell the most frequent color available at the current price, then immediately sell the most frequent remaining color at the same price (or next price if you can't pair). Binary search often appears in editorials because you're checking if a given profit is achievable, but the primary pattern is heap-based greedy ordering. Array manipulation, sorting, and priority queue operations are all here. Most candidates get stuck thinking linearly about the problem instead of recognizing the constraint as a scheduling problem. StealthCoder's real value here is surfacing the correct heap interaction pattern when time pressure makes pattern-spotting hard.
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Sell Diminishing-Valued Colored Balls 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. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Sell Diminishing-Valued Colored Balls interview FAQ
Is this really a Medium, or does 30% acceptance suggest it's harder?+
The 30% acceptance rate is genuinely reflective of Medium difficulty at companies like Groupon and MathWorks. It's not algorithmically complex, but the greedy constraint is unintuitive. Most fails come from not recognizing the pairing pattern, not from implementation.
Do I need Binary Search for this problem?+
Binary search is optional, not required. Some solutions use it to verify feasibility of a profit threshold. The core solution is greedy with a priority queue. Learn the heap-based greedy approach first, then consider binary search as an optimization if you want to clarify intent.
What's the trap that kills candidates on this one?+
Thinking you can just sell all of the most frequent color first. You can't. You'll bottleneck and be forced to sell at price 1. The trick is interleaving: always sell the top two most frequent colors together at the current price, respecting the pairing constraint.
Does Groupon or MathWorks ask this with a specific language requirement?+
Both companies appear in reports for this problem, but language constraints vary by role and cycle. Assume you'll see it in your primary interview language. The algorithm is the same regardless of implementation.
How does this relate to the other topics listed, like Array and Sorting?+
You'll use sorting to initialize your data and potentially Array operations for manipulation. But the heavy lifting is in the priority queue (Heap) and greedy ordering. The Math aspect is calculating cumulative profit once you know the sell sequence.
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