Min Diff
Reported by candidates from Oracle's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Oracle's Min Diff question showed up in February 2024 and it's a straightforward but easy-to fumble array problem. You're given an array and need to find the minimum difference between any two elements. The trap is thinking you need a fancy algorithm when sorting solves it in one pass. This is the kind of problem where candidates overthink and lose time. If you blank during the OA, StealthCoder will feed you the pattern in seconds so you can code with confidence instead of spiraling.
Pattern and pitfall
Min Diff is a classic two-pointer setup after sorting. Sort the array, then walk through adjacent pairs and track the smallest gap. The insight is that the minimum difference must occur between consecutive elements in a sorted array, so you never need to compare distant pairs. The common mistake is trying to solve it with nested loops or hash maps, burning time on complexity you don't need. During the live OA, if you freeze on the approach, StealthCoder acts as a safety net, giving you the sorted two-pointer pattern so you can implement confidently and move on to harder problems.
Memorize the pattern. If you can't, run StealthCoder. The proctor sees the IDE. They don't see what's behind it.
You can drill Min Diff cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Made by an engineer who treats the OA as theater. If yours is tonight, you don't have time to grind. You have time to hedge.
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Oracle reuses patterns across OAs. Made by an engineer who treats the OA as theater. If yours is tonight, you don't have time to grind. You have time to hedge. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Min Diff FAQ
Is Min Diff actually hard, or am I just overthinking it?+
You're overthinking. It's a warm-up difficulty question. Sort, iterate adjacent pairs, track min. The only trick is remembering that sorting puts the closest elements next to each other. Don't spend more than 10 minutes on this one.
Do I need a hash map or two pointers here?+
Two pointers after sorting. Hash maps add complexity without benefit. Sort in O(n log n), then iterate in O(n). That's it. Clean, fast, what Oracle expects.
What if the array has duplicates?+
After sorting, the minimum difference is at least 0 if duplicates exist. Your loop will naturally find it. No special case needed. Just iterate and compare.
How do I prepare for this in 48 hours?+
Don't cram. Understand the sorting insight: closest elements sit adjacent after sort. Code it once, trace through an example with duplicates and negatives. That's enough. Oracle doesn't expect exotic optimizations here.
Will Oracle ask this exact problem again?+
Pattern like this is evergreen in Oracle OAs. The specific values change, the algorithm doesn't. Know sorted two-pointer cold. It's foundational.