Encircular
Reported by candidates from Goldman Sachs's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Goldman Sachs ran Encircular in January 2024, and it's a geometry problem that trips up candidates who try to brute-force it. You'll be given points or shapes and need to determine something about encirclement, containment, or circular boundaries. The trick is recognizing when you need computational geometry instead of naive point-checking. StealthCoder can surface the pattern instantly if you blank on the setup, so you're not starting from zero in the live assessment.
Pattern and pitfall
Encircular likely involves determining whether points lie within a circle, finding the smallest enclosing circle, or validating circular containment. The naive approach, checking every point against every circle or iterating brute-force, will time out. The real solution usually involves geometric properties: distance calculations, circle equations, or convex hull techniques. Common pitfall: floating-point precision errors when comparing distances. You might also need to handle edge cases like collinear points or duplicate coordinates. If you hit a wall during the OA, StealthCoder will show you the geometric formula and the optimization without breaking your proctor's view.
If you see this problem in your OA tomorrow, the play is to recognize the pattern in 30 seconds. StealthCoder buys you that recognition.
You can drill Encircular 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 passed his OA cold and still thinks the filter is broken.
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Goldman Sachs reuses patterns across OAs. Built by an Amazon engineer who passed his OA cold and still thinks the filter is broken. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Encircular FAQ
Is this actually a geometry problem or is there a trick?+
It's a real geometry problem. There's no clever math shortcut to avoid the distance calculations or circle logic. The 'trick' is using the right algorithm (Welzl's algorithm for smallest enclosing circle, or similar) instead of brute force. Know your computational geometry basics before the OA.
How do I prepare for Encircular in 24 hours?+
Review circle equations, distance formulas, and how to check if a point is inside a circle. If the problem is about the smallest enclosing circle, understand Welzl's algorithm conceptually. Practice one or two geometry problems to warm up. Avoid memorizing code; focus on the logic.
Will floating-point errors tank my solution?+
Possibly. Use an epsilon value for comparisons, especially when checking if a point lies exactly on the boundary. Test with edge cases like points at the origin or on axes. Goldman Sachs OAs usually have tight test cases, so precision matters.
What if I don't recognize the geometry pattern?+
Read the problem carefully. If you see 'circle', 'enclose', 'contain', or 'boundary', it's geometry. Start with a brute-force solution and optimize. If you're still stuck, that's exactly when StealthCoder steps in to show you the pattern without the proctor seeing it.
Is this problem still asked by Goldman Sachs?+
It was reported in January 2024, so yes, it's recent. Goldman Sachs uses geometry problems to test spatial reasoning and algorithmic thinking. Expect similar problems in future rounds. This isn't a one-off.