Min Difference
Reported by candidates from IBM's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
IBM threw a Min Difference problem at candidates in December 2024, and it's a classic sorting trap disguised as a math question. You're looking at an array and trying to minimize some difference between elements. Candidates typically overthink this as dynamic programming when it's really about order. If you blank on the live OA, StealthCoder reads the exact problem text and feeds you the pattern in seconds, so you don't panic and write brute force.
Pattern and pitfall
Min Difference almost always boils down to sorting the array first, then comparing adjacent or windowed elements. The key insight: if you want to minimize distance between any pair, they must be neighbors in sorted order. No DP needed. The trap is candidates try to track state or build tables when the answer lives in O(n log n) sort plus a linear scan. Common variants ask for the smallest gap between any two numbers, or the minimum difference after removing k elements. Once sorted, it's pattern matching on what 'difference' means in context. StealthCoder's real value here is catching the exact variant IBM used, since problem text variations shift the approach slightly.
If this hits your live OA and you blank, StealthCoder solves it in seconds, invisible to the proctor.
You can drill Min Difference 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. Built by an Amazon engineer who would have shipped this the night before his JPMorgan OA if he'd had it.
Get StealthCoderRelated leaked OAs
This OA pattern shows up on LeetCode as minimize the maximum difference of pairs. If you have time before the OA, drill that.
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Make sure you actually pass IBM's OA.
IBM reuses patterns across OAs. Built by an Amazon engineer who would have shipped this the night before his JPMorgan OA if he'd had it. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Min Difference FAQ
Is this a sorting problem or DP?+
Sorting. After you sort, the answer emerges from adjacent pairs or a fixed window. DP would be massive overkill and a red flag that you're overcomplicating it. If your solution needs memoization or a table, you're on the wrong track.
Do I need to consider all pairs?+
No. In a sorted array, the minimum difference is always between consecutive elements or within a sliding window of fixed size. Checking all pairs is O(n^2) and unnecessary. Sort first, scan once.
What if the array has duplicates?+
Duplicates make the answer zero if you're looking for any pair difference. Sorting still works. If the problem says no duplicates or has extra constraints, read carefully. The sorted array handles it either way.
How do I prepare this in 48 hours?+
Recognize the pattern: sort, then iterate. Practice one or two LeetCode sorting problems to warm up your instinct. The hard part is reading the exact constraints IBM gave you. StealthCoder handles that on the day.
Will IBM ask a variant or the textbook version?+
Likely a small twist like 'remove k elements first' or 'minimize max difference in groups.' The core approach stays the same: sort, then reason about what constraint changes the scan logic. The pattern is stable across variants.