Merge Arrays
Reported by candidates from Oracle's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Oracle's 'Merge Arrays' question hit candidates in February 2024, and it's a straightforward array operation that tests whether you can handle the mechanics under pressure. You've got two sorted arrays. The ask is simple: combine them into a single sorted result. It's the kind of problem that feels easy until you're in the OA and your brain goes blank on edge cases. StealthCoder reads the exact input format and delivers the merge strategy in seconds, so you're not burning time on a question you should own.
Pattern and pitfall
The trap here is implementation detail, not algorithm. Most candidates know they need to merge two sorted arrays and the result should be sorted. The pattern is array manipulation with a two-pointer approach: start at the beginning of each array, compare elements, and place the smaller one into a result array. If you're working in-place on one array (a common variant), you need to avoid overwriting unprocessed elements. Common failure: off-by-one errors when handling the tail of one array after the other is exhausted. When you're live in the OA and second-guessing the index boundaries, StealthCoder gives you the exact loop condition to run.
The honest play: practice the pattern, and have StealthCoder ready for the one you didn't see coming.
You can drill Merge Arrays 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 for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play.
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This OA pattern shows up on LeetCode as merge sorted array. If you have time before the OA, drill that.
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Oracle reuses patterns across OAs. Built for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Merge Arrays FAQ
Is this really asking for a two-pointer merge or something else?+
It's the classic two-pointer merge. Compare the heads of both arrays, append the smaller element to a result, advance that pointer. Time O(n + m), space O(n + m) for a new array. If they ask in-place, you'll need a different strategy, but the OA description will make that clear.
What's the one thing I'll get wrong if I code fast?+
Handling the remainder when one array is exhausted. After your main loop, one array will have leftover elements. You can't just forget them. Copy the tail of whichever array has elements left. That's the pitfall that tanks submissions.
Do I need to handle empty arrays?+
Yes. If one array is empty, your result is just the other array. If both are empty, your result is empty. A solid solution checks these cases early and returns fast. The OA will test at least one edge case.
How long should this take me in the OA?+
Five to eight minutes to code and test if you're confident. Two-pointer merge is a classic pattern you should be able to write without thinking. If you're stuck, that's where a safety net tool helps you move forward on the next question.
Will Oracle ask follow-ups like merge sorted lists or merge k arrays?+
Possible. Merge k arrays is harder and uses a min-heap or divide-and-conquer. If you nail the two-array version, you'll have the foundation for both. Start with the OA problem as written. Don't overthink variants.