Capital One·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

May 2026

Summary

Capital One SWE interview with a single coding problem that looked like a clean simulation at first glance but had enough edge cases to keep me second-guessing myself the whole time.

Questions Asked (1)

You're given an array of warehouse capacities and a list of operations. Each operation is either 'PACKAGE' (assign one package to the next available warehouse in round-robin order) or 'CLOSURE idx' (permanently disable that warehouse). Warehouses are skipped if closed or full. If a full round-robin scan finds every active warehouse is full, reset all active warehouses to their original capacities and continue assigning. Track how many packages each warehouse handles. After all operations, return the index of the warehouse with the most packages handled, breaking ties by largest index.

Algorithms & Data Structures

Author's notes

The round-robin part was fine, I've done similar things.

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AI HintsAI Generated

Suggested Approach

Clarify the problem constraints and edge cases, then propose an efficient simulation using a circular linked list or an ordered set to skip closed/full warehouses. Walk through the algorithm step-by-step, analyze time complexity, and test with examples including tie-breaking and reset scenarios.

Pro tip: Mention that using a balanced BST or a circular linked list can reduce the time complexity of finding the next available warehouse from O(n) per operation to O(log n) or O(1) amortized, demonstrating awareness of performance trade-offs.

1. Clarify requirements and edge cases

Ask questions to confirm details: initial capacities, handling of invalid closures, reset behavior when all active warehouses are full, and tie-breaking rules. Identify edge cases like no active warehouses, all full, or closures of already closed warehouses.

2. Design data structures

Choose structures to track warehouse states (capacity, current load, closed flag) and to efficiently find the next available warehouse. Consider a circular linked list of active warehouses or an ordered set with a pointer for round-robin traversal.

3. Outline algorithm steps

Describe the simulation: for PACKAGE, find next active non-full warehouse, assign package, update load; if none, reset all active warehouses to original capacities and assign to the first active warehouse. For CLOSURE, mark warehouse as closed and remove from active set.

4. Analyze complexity and optimize

Discuss time and space complexity. For naive approach O(n) per operation; with optimized structures O(log n) or O(1) amortized. Mention trade-offs and potential improvements.

5. Test with examples and edge cases

Walk through a small example, including a reset scenario and tie-breaking. Verify correctness and discuss how to handle ties (choose largest index).

Key Points to Mention

Use of a circular linked list or balanced BST to efficiently find the next available warehouse.
Handling of reset when all active warehouses are full: reset loads to original capacities and continue.
Tie-breaking rule: when multiple warehouses have the same max packages, return the one with the largest index.
Time complexity analysis: naive O(n) per operation vs optimized O(log n) or O(1) amortized.
Edge cases: no active warehouses, closure of already closed warehouse, all warehouses full initially.
Space complexity: O(n) for storing warehouse states and auxiliary structures.

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