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Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Google SWE interview with a geometry/algorithm problem that sounds deceptively clean but has a few layers to it. The double binary search approach is the key insight and I'm not sure I would've landed on it cleanly under pressure.

Questions Asked (1)

Q1

You're given a cake represented as a sequence of segments, each with an associated area. Find a straight cut that divides the total area exactly in half.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The problem looks like a math puzzle at first and I probably would've spent too long trying to derive some closed-form formula.

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AI HintsAI Generated

Suggested Approach

First, clarify the problem constraints: whether the cake is a 1D sequence of segments (like a strip) or a 2D shape, and whether the cut must be straight and perpendicular to the sequence. Then, model the problem as finding a cut point where the cumulative area from one end equals half the total area, using prefix sums for efficiency. Discuss trade-offs between different interpretations and algorithms, and consider edge cases like multiple valid cuts or non-contiguous segments.

Pro tip: Demonstrate maturity by explicitly stating assumptions and asking clarifying questions before diving into a solution; this shows you think like a Google engineer who values problem understanding over premature coding.

1. Clarify the problem

Ask questions to understand the cake's geometry, the cut's constraints (straight, direction), and what 'divides exactly in half' means (area-wise). Confirm if the cake is a 1D sequence or 2D shape.

2. Define the model

Represent the cake as an array of segment areas. If 1D, a straight cut is a point between segments; if 2D, a straight line. For simplicity, assume 1D and cuts perpendicular to the sequence.

3. Develop an algorithm

Compute total area, then use prefix sums to find a cut point where the left area equals half the total. If no exact cut exists, discuss approximations or alternative cuts.

4. Analyze complexity and trade-offs

The prefix sum approach is O(n) time and O(1) extra space. Discuss if a binary search could work if segments are sorted, or if the problem requires a geometric solution for 2D.

5. Test with edge cases

Consider cases like total area odd, multiple valid cuts, cuts through a segment (if allowed), and non-uniform segment sizes. Verify the solution handles them.

Key Points to Mention

  • Prefix sums for efficient cumulative area calculation
  • Time and space complexity: O(n) time, O(1) space
  • Handling of odd total area (impossible to divide exactly in half)
  • Assumption of 1D sequence vs. 2D cake geometry
  • Multiple valid cuts and how to choose one
  • Edge cases: zero-area segments, single segment, empty input

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