Amazon Software Development Engineer Interview Questions and Answers

Find the mirror node in a binary tree, which is the corresponding node in the mirrored version of the tree.

• A mirror node of a binary tree is found by swapping left and right children at each level.

• To find a mirror node for a given node, traverse the tree recursively.

• Example: For a node with value 5, its mirror node in a mirrored tree would be the node that corresponds to its position in the original tree.

• Use depth...read more

Efficiently find the median in a continuous stream of integers using two heaps.

• Use two heaps: a max-heap for the lower half and a min-heap for the upper half.

• Insert new numbers into the appropriate heap based on their value.

• Balance the heaps to ensure their sizes differ by at most one.

• The median is the root of the max-heap if it has more elements, or the average of both roots if they are equal in size.

• Example: Str...read more

Detecting cycles in a directed acyclic graph (DAG) using dynamic programming techniques.

• A directed acyclic graph (DAG) has no cycles by definition.

• To check for cycles, perform a topological sort.

• If a topological sort is possible, the graph is acyclic.

• Example: In a graph with edges (1->2, 2->3), topological sort yields [1, 2, 3].

• If you encounter a node that is already in the current path, a cycle exists.

Designing a low-level architecture for Uber's ride-sharing platform focusing on key components and interactions.

• User Management: Handles user profiles, authentication, and authorization.

• Ride Management: Manages ride requests, cancellations, and ride history.

• Driver Management: Tracks driver profiles, availability, and ratings.

• Geolocation Service: Provides real-time location tracking for users and drivers.

• Pricing En...read more

I improved a product feature decision by analyzing user engagement metrics, leading to a more effective design.

• Identified a drop in user engagement metrics for a specific feature.

• Conducted A/B testing to compare user interactions with different designs.

• Analyzed data showing a 30% increase in engagement with the new design.

• Presented findings to the team, leading to a decision to implement the changes.

Design a system for booking tickets for events like movies, concerts, etc.

• Use microservices architecture for scalability and flexibility

• Implement a user-friendly interface for easy ticket booking

• Include features like seat selection, payment gateway integration, and booking history

• Utilize a database to store event details, user information, and booking records

Design system design for bitly

• Use a distributed system architecture to handle high traffic and scalability

• Implement a URL shortening algorithm to generate unique short links

• Utilize caching mechanisms to improve performance and reduce database load

• Include analytics and tracking features to monitor link performance

• Ensure data security and privacy measures are in place to protect user information