Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Apr 2026

Summary

Meta SWE screen, one coding problem about shipping capacity. Pretty standard stuff, nothing too wild.

Questions Asked (1)

Given a list of package weights and a number of days D, find the minimum ship capacity needed to deliver all packages within D days.

Algorithms & Data Structures

Author's notes

Binary search on the answer.

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AI HintsAI Generated

Suggested Approach

Recognize this as a classic binary search on the answer problem: the minimum capacity lies between the maximum package weight and the sum of all weights. For a given capacity, simulate the shipping process greedily to check if all packages can be delivered within D days. Binary search for the smallest capacity that satisfies the condition.

Pro tip: Clarify edge cases upfront, such as when D is less than the number of packages (impossible) or when D is very large (capacity equals max weight). Also, mention that the greedy simulation is optimal because any feasible schedule must load packages in order, and taking as many as possible each day never hurts.

1. Define search bounds

Set low to the maximum package weight (must carry the heaviest package) and high to the sum of all weights (carry everything in one day).

2. Design feasibility check

Write a function that, given a capacity, simulates loading packages in order, counting days needed. Return true if days <= D.

3. Binary search for minimum capacity

While low < high, compute mid, check feasibility. If feasible, search left (high = mid); else search right (low = mid + 1).

4. Return result and analyze complexity

Return low as the minimum capacity. Time complexity O(n log(sum - max)), space O(1).

Key Points to Mention

Binary search on the answer space (capacity) rather than on the array.
Greedy simulation for feasibility: load packages in order, start a new day when capacity exceeded.
Lower bound is max(weights) because a ship must carry the heaviest package.
Upper bound is sum(weights) because one day can carry all packages.
Time complexity: O(n log S) where S = sum(weights) - max(weights).
Edge cases: D >= n (answer = max weight), D < 1 (invalid), or impossible if D < n? Actually D can be less than n if capacity allows multiple packages per day, but if D < number of packages, it's still possible if capacity is large enough? Wait, if D < n, you can still deliver multiple packages per day, so it's possible. But if D is 0, impossible. So mention D must be at least 1.

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