Find the Array Concatenation Value
A easy-tier problem at 71% community acceptance, tagged with Array, Two Pointers, Simulation. Reported in interviews at IBM and 0 others.
You're facing a problem that looks like it should take 30 seconds, and it might in your prep session. But on the live OA, small simulation problems like this trip up candidates who overthink or misread the problem spec. Find the Array Concatenation Value is asked by IBM and sits at 71% acceptance, which means almost a third of test-takers fail it, usually because they misunderstand the concatenation operation or mess up the two-pointer traversal. If you blank on the exact mechanics during the assessment, StealthCoder solves it invisibly in seconds, letting you move to the next problem without derailing your entire session.
Companies that ask "Find the Array Concatenation Value"
Find the Array Concatenation Value 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 trick isn't algorithmic complexity, it's mechanical precision. You've got an array, and you're removing elements from both ends, concatenating them as strings (not adding them numerically), and summing those concatenation values. Candidates often default to numeric addition instead of string concatenation, or they lose track of the pointers converging from opposite ends. The simulation itself is straightforward: two pointers, left and right, move inward until they meet or cross. The real wall is usually just that you haven't carefully read whether you're concatenating as strings and then converting to int, or some variation of that operation. It's a test of whether you can follow instructions precisely under pressure, not a test of algorithmic insight. StealthCoder surfaces the exact input-output trace immediately, so you can verify your pointer logic on the spot.
Pattern tags
You know the problem.
Make sure you actually pass it.
Find the Array Concatenation Value 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.
Find the Array Concatenation Value interview FAQ
Is this problem actually easy or are the acceptance numbers misleading?+
At 71% acceptance, it's genuinely easy algorithmically. The failures are almost always from misreading the problem spec: forgetting to concatenate as strings, or confusing which operation to perform on the pointers. If you implement the simulation carefully, you'll pass.
When IBM asks this, what are they really testing?+
Not algorithm knowledge. They're testing whether you read carefully, implement what's asked (not what you think should be asked), and manage state cleanly. It's a gate for attention to detail.
What's the most common mistake on this problem?+
Treating concatenation as numeric addition instead of string concatenation. Another common trap is forgetting to handle the case where left and right pointers meet or cross, or off-by-one errors in the pointer loop condition.
How does two pointers apply here?+
You initialize left at index 0 and right at the last index. You pop from both ends, concatenate their string representations, convert back to int, and sum. The pointers move inward until they meet. It's a straightforward traversal, not a search or partition.
Should I worry about this problem showing up in my OA?+
Not particularly, unless you're interviewing at IBM. At 71% acceptance and easy difficulty, it's a warm-up problem. But if it does appear and you blank, that's exactly what StealthCoder handles: invisible, live feedback so you move on without panic.
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