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Toma·Frontend Engineer·Technical Phone Screen·Intermediate

Intermediate
Jul 2026

Summary

Interviewed for a frontend role at Toma and got a math-flavored coding problem that I wasn't really expecting. Pretty short technical screen, just the one question as far as I could tell.

Questions Asked (1)

Q1

Given an array of points in a unit square, write a function that uses the fraction of points falling inside a quarter circle of radius 1 to approximate pi.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Monte Carlo estimation dressed up as a frontend coding question.

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AI HintsAI Generated

Suggested Approach

Start by explaining the Monte Carlo method: the ratio of points inside the quarter circle to total points approximates π/4, so π ≈ 4 * (inside / total). Then outline the function: generate random points in the unit square, check if x² + y² ≤ 1, count inside, and return the estimate. Finally, discuss trade-offs like accuracy vs. number of points and potential optimizations.

Pro tip: Mention that you can use a deterministic approach like a grid or Halton sequence for better convergence, but for simplicity and speed, random points are fine. Also, note that the estimate converges as O(1/√n), so for 1% accuracy you need about 10,000 points.

1. Explain the Monte Carlo principle

Describe how the ratio of points inside the quarter circle to total points approximates π/4, leveraging the area ratio. This sets the mathematical foundation.

2. Outline the algorithm

Detail the steps: generate N random points in [0,1]x[0,1], count how many satisfy x² + y² ≤ 1, then compute π ≈ 4 * (inside / N).

3. Discuss implementation details

Mention using Math.random() for point generation, a loop for counting, and returning the estimate. Highlight that the function should be pure and testable.

4. Analyze trade-offs and accuracy

Talk about how the number of points affects accuracy (error ~ 1/√N), and the trade-off between precision and performance. Suggest ways to improve, like using a deterministic sequence or increasing N.

5. Consider edge cases and optimizations

Mention handling N=0 or very small N, and potential optimizations like vectorization or using a typed array for performance in JavaScript.

Key Points to Mention

  • Monte Carlo method and area ratio
  • Formula: π ≈ 4 * (points inside quarter circle) / total points
  • Time complexity O(N) and space O(1)
  • Accuracy scales with 1/√N (standard error)
  • Use of Math.random() for uniform distribution
  • Potential improvements: quasi-random sequences, increasing N, or using a grid

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.