Sort Transformed Array
A medium-tier problem at 57% community acceptance, tagged with Array, Math, Two Pointers. Reported in interviews at LinkedIn and 0 others.
Sort Transformed Array shows up in LinkedIn technical assessments and catches people off guard because the obvious approach wastes time. You're given a sorted array and a quadratic function f(x) = ax^2 + bx + c. The trick isn't to apply the function and re-sort: that's O(n log n) and signals you missed the problem. The real constraint is that the input array is already sorted, and the output can be computed in a single O(n) pass if you understand where the extremes land on a parabola. If this hits your live assessment and you blank on the pattern, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Sort Transformed Array"
Sort Transformed Array 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 an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoderThe problem hinges on the shape of the parabola defined by f(x). If the coefficient a is zero, you're just doing a linear transformation. If a is positive, the parabola opens upward: the smallest and largest transformed values sit at the edges of the input range or the vertex, depending on where the axis of symmetry falls. If a is negative, it opens downward and the extremes flip. The two-pointer approach builds the output array from both ends inward, placing the largest (or smallest, depending on a's sign) values at the output boundaries. Candidates often apply the function to all elements, sort, and submit, burning precious minutes. Understanding the parabola's geometry and using two pointers is the hedge StealthCoder provides if you freeze during the live OA.
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Sort Transformed Array recycles across companies for a reason. It's medium-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 an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Sort Transformed Array interview FAQ
Is this really asked at LinkedIn?+
Yes, it appears in their technical assessments. The acceptance rate is below 60 percent, so it's not trivial. It's the kind of problem they use to separate candidates who pattern-match from those who actually think through the math.
What's the trick I'm missing if I just sort the transformed array?+
Sorting is O(n log n). The trick is the input is already sorted. If you understand parabola geometry, you build the sorted output in O(n) by comparing transformed values at the array edges and filling the result from both ends. The parabola's shape tells you where extremes land.
How does two pointers apply here?+
Since f(x) is a parabola, the extremes of the transformed range sit at the edges or vertex of the input. Use two pointers at the array start and end, compute f for both, place the larger (or smaller, depending on a) in the result array, then move the pointer inward. This builds a sorted output without re-sorting.
What if the coefficient a is negative or zero?+
If a = 0, it's linear and the output follows the sign of b. If a < 0, the parabola opens downward, so extremes are at the input edges. If a > 0, it opens upward, and the minimum might be near the vertex. Recognizing these cases lets you adjust which end of the output you fill first.
Should I memorize this or understand it conceptually?+
Understand the parabola geometry. Draw a quick sketch during the assessment if you're stuck. The two-pointer pattern follows naturally once you see where the extremes land. This approach also generalizes to similar problems, so conceptual understanding pays off more than rote memorization.
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