Number of Unique Flavors After Sharing K Candies
A medium-tier problem at 60% community acceptance, tagged with Array, Hash Table, Sliding Window. Reported in interviews at ciena and 0 others.
You're sitting down for a take-home or live OA and hit a problem about sharing candies and counting unique flavors. It looks like a simple loop or count, but the trick lives in the constraints: you're restricted to a specific window of K candies, and you need to track what's unique at each step. Ciena has asked this one. The acceptance rate sits at 59.7%, which means nearly 40% of candidates either miss the sliding window pattern or miscount the unique values. If you haven't drilled this specific combination of array iteration and hash table state tracking, StealthCoder solves it invisibly during your assessment, surfacing a working solution in seconds when you hit the wall.
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Number of Unique Flavors After Sharing K Candies 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 for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe problem wraps Array, Hash Table, and Sliding Window together. You'll iterate through candies, maintain a window of K items, and count distinct flavors in that window at each valid position. The trap: candidates either use a naive O(n*k) recount at each step, or they forget that the window slides forward, meaning elements drop out of scope. The efficient move is a hash map or set to track current flavors in the active window, updating it as you slide. When you add a candy to the window, increment its count. When the window exceeds K, remove the oldest candy and decrement its count, then purge it from the map if count hits zero. By the time you've slid all the way through, you'll have collected the unique count at each valid position. This is where the pattern clicks: hash table manages membership, array pointer handles the window boundary. On a live OA, if the window logic trips you up or you blank on the hash map update, StealthCoder surfaces the exact approach without the proctor seeing a thing.
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Number of Unique Flavors After Sharing K Candies 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 for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Number of Unique Flavors After Sharing K Candies interview FAQ
Is this problem still asked in 2024-2025?+
Yes. Ciena has it on record. The acceptance rate of 59.7% suggests it's fresh enough that candidates still stumble on it. It's not a household-name problem like Two Sum, so you can't rely on pre-drilled instinct. That's exactly why the sliding window twist catches people off guard.
What's the actual trick that makes it medium, not easy?+
The trick is that you can't just count unique flavors once. You have to do it at every valid window position as you slide, and the hash table state must update correctly each time an element enters or leaves the window. Forgetting to remove elements when the window slides forward is the most common miss.
How does the sliding window connect to the hash table here?+
The hash table stores the flavor count of candies currently in the window. As you slide, you add new candies to the map and increment their counts. When the window exceeds K, you decrement the oldest candy's count and remove it from the map if count reaches zero. The map itself tells you unique flavors at each step.
What's the time complexity and why does it matter?+
O(n) where n is the array length. You visit each candy once, and hash table operations are O(1). A naive solution recounting unique flavors at every position is O(n*k) and fails on large inputs. Knowing the difference matters for passing test cases, not just correctness.
Will I definitely get this in my OA?+
Unknown. Only Ciena is recorded here, and the problem isn't universally famous. But if you hit it cold during a screen-share assessment and the window pattern doesn't click, StealthCoder runs invisibly and gives you the solution in seconds, so you move on without blanking.
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