Alternating Groups I
A easy-tier problem at 68% community acceptance, tagged with Array, Sliding Window. Reported in interviews at Samsara and 0 others.
Alternating Groups I is an easy array problem that's been asked at Samsara. With a 67% acceptance rate, it looks straightforward until you realize the catch: you need to spot when elements alternate in a circular pattern, and the naive approach often misses edge cases at the boundary. If you blank on how to handle the wraparound during your live OA, StealthCoder will surface a clean sliding window solution in seconds, invisible to the proctor. This is the kind of problem where the pattern is obvious once you see it, but getting it wrong costs you the entire question.
Companies that ask "Alternating Groups I"
Alternating Groups I 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 trick is recognizing that 'alternating' means no two adjacent elements are equal, and the array wraps around. A sliding window approach works, but you can't just scan left to right and stop at the end. You need to either treat the circular structure explicitly by appending the start of the array to the end, or use modulo arithmetic to wrap indices. Most candidates who fail this problem either ignore the circular property entirely, or they build a window correctly but crash on index boundaries. The pattern itself is simple: track the longest sequence where elements alternate, and account for the fact that position 0 and position n-1 are neighbors. If you hit this in an assessment and the wraparound logic isn't clicking, StealthCoder executes the correct window mechanics while you stay calm.
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Alternating Groups I recycles across companies for a reason. It's easy-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.
Alternating Groups I interview FAQ
What makes this problem different from a standard alternating-element problem?+
The array is circular, so the last element is adjacent to the first. Many candidates miss this and treat it as a linear array. The solution must account for the wraparound. Using a sliding window on a doubled or modulo-indexed view of the array handles this cleanly.
Is 67% acceptance rate typical for an easy problem?+
Not really. Most easy problems sit higher. The 67% here reflects that the circular property trips up people who assume a linear structure. It's easy to code, hard to get right on first try without mental clarity on the edge case.
What's the sliding window size strategy?+
You don't have a fixed window size. Instead, you expand the window as long as consecutive elements alternate, then move the start pointer forward. Track the maximum window size seen. Restart the window when the alternating property breaks.
Do I need to actually duplicate the array to handle the circular case?+
No. You can iterate up to 2*n and use modulo arithmetic, or append n elements from the start to the end, or be clever with index logic. All work. Doubling is simpler to code and less error-prone than modulo indexing.
Is this problem still asked despite being easy?+
It's been reported at Samsara. Easy problems are common filters in interviews. They verify you can code cleanly under pressure. If you freeze on this during your OA, it's a wasted slot. That's where StealthCoder's invisible hedge matters most.
Want the actual problem statement? View "Alternating Groups I" on LeetCode →