Apple·Machine Learning Engineer·Technical Phone Screen·Senior

Senior

Jun 2026

Summary

Apple MLE interview with a binary search coding problem. Nothing too wild but the constraint range on h made it easy to overthink the search bounds.

Questions Asked (1)

Given n piles of bananas and h hours before guards return, find the minimum eating speed k (bananas per hour) such that all piles are finished in time. Each hour you eat from one pile only, and if the pile has fewer than k bananas you just finish it.

Algorithms & Data Structures

Author's notes

Classic binary search on the answer.

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AI HintsAI Generated

Suggested Approach

Recognize that the minimum eating speed can be found using binary search on the answer space from 1 to max(piles). For each candidate speed, simulate the total hours needed and adjust the search range accordingly. This yields an O(n log m) solution, where m is the maximum pile size.

Pro tip: Mention that the problem is a classic application of binary search on the answer, and that the time complexity is optimal. Also, clarify that the simulation uses ceiling division to compute hours per pile.

1. Understand the problem

Restate the problem: find the minimum integer k such that the total hours to eat all piles, where each pile takes ceil(pile/k) hours, is ≤ h.

2. Define search space

The possible speeds range from 1 to the maximum pile size. Speeds below 1 are invalid, and speeds above max(piles) don't reduce time further.

3. Binary search for minimum k

While low ≤ high, compute mid, calculate total hours with speed mid, and if total ≤ h, record mid as a candidate and search left; else search right.

4. Implement hours calculation

For a given speed k, sum ceil(pile/k) for all piles. Use integer arithmetic: (pile + k - 1) // k to avoid floating point.

5. Return the result

After binary search, return the smallest k that satisfies the condition.

Key Points to Mention

Binary search on the answer space (speed k) rather than on the piles.
Time complexity: O(n log m), where n is number of piles and m is max pile size.
Space complexity: O(1) extra space.
Use of ceiling division to compute hours per pile.
Monotonicity: if a speed k works, any speed > k also works, enabling binary search.
Edge cases: h < n (impossible), h very large (minimum speed 1).

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