DoorDash·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

DoorDash coding round for a software engineer role, one problem focused on building out pay calculation logic for delivery drivers. Pretty domain-specific but not algorithmically brutal.

Questions Asked (1)

Write a function to calculate a delivery driver's total pay given inputs like base pay, distance traveled, time spent, tips, and any active bonuses or promotions.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

The problem itself isn't hard algorithmically but I spent too long trying to figure out edge cases before writing a single line.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and edge cases, then design a clean function signature with well-defined inputs and outputs. Implement the core calculation with modular components for each pay element, and discuss trade-offs like extensibility, precision, and performance.

Pro tip: Mention that monetary values should be handled in cents or with decimal libraries to avoid floating-point errors, and that the design should be easily extensible for new bonus types.

1. Clarify Requirements

Ask questions to understand the exact pay formula, input formats, edge cases (e.g., zero distance, negative tips), and whether bonuses are additive or multiplicative.

2. Define Function Signature

Specify the function name, parameters (base pay, distance, time, tips, bonuses), and return type, considering whether to use a struct/object for inputs.

3. Implement Core Calculation

Write the logic to compute total pay, breaking it into sub-calculations for each component and handling any conditional bonuses.

4. Handle Edge Cases and Validation

Add checks for invalid inputs (e.g., negative values) and ensure the function behaves gracefully, possibly throwing exceptions or returning errors.

5. Discuss Trade-offs and Extensibility

Talk about design choices: using a configuration object for bonuses, separating calculation from data retrieval, and ensuring the function is testable and maintainable.

Key Points to Mention

Use integer cents or a decimal library to avoid floating-point precision issues with money.
Design for extensibility: allow new bonus types to be added without modifying core logic (e.g., strategy pattern or list of bonus rules).
Consider performance: the calculation should be O(1) or O(n) where n is number of bonuses, and avoid unnecessary computations.
Validate inputs: ensure non-negative values for base pay, distance, time, and tips; handle null/undefined bonuses.
Write unit tests covering typical cases, edge cases (zero values, large numbers), and bonus combinations.
Document assumptions: e.g., whether time and distance are used in base pay calculation or are separate components.

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