Feature Selection and Dimensionality Reduction: PCA, Lasso, and Tree Importance
Feature selection and dimensionality reduction are how you fight the curse of dimensionality — the phenomenon where models trained on […]
AI/ML Interview Questions
System Design
Design a Proximity Service (Yelp / Nearby Search)
Design a proximity service like Yelp’s “restaurants near me” or Google Maps’ nearby search. The core challenge is geospatial indexing
System Design
Design a Hotel / Airbnb Reservation System
Design a hotel or vacation rental reservation system like Booking.com or Airbnb. The core challenge isn’t the search UI —
AI/ML Interview Questions
Cross-Validation Strategies: K-Fold, Time Series, and Nested CV
Cross-validation is how you estimate a model’s generalization performance before deploying it. Getting this wrong — especially data leakage —
System Design
Design a Payment System
Design a payment system like Stripe, PayPal, or an internal payments platform at a company like Uber or Amazon. This
System Design
Design a News Feed (Facebook-style)
Design a news feed system like Facebook’s. This is a richer problem than the Twitter feed design — Facebook’s feed
System Design
Design a Distributed Key-Value Store
Design a distributed key-value store like DynamoDB, Cassandra (its KV layer), or Redis Cluster. This is one of the most
AI/ML Interview Questions
Classification Metrics: Precision, Recall, F1, and AUC-ROC
Classification metrics are one of the most frequently misused concepts in ML interviews. The wrong answer: “I use accuracy.” The
System Design
Design Dropbox / Google Drive
Design a file storage and sync service like Dropbox or Google Drive. This problem tests your ability to handle large
System Design
Design a Web Crawler
Design a web crawler that can index a significant portion of the internet. This question tests whether you understand distributed
AI/ML Interview Questions
How Backpropagation Works: The Chain Rule in Neural Networks
Backpropagation is the algorithm that makes training deep neural networks possible. Every interviewer for ML engineering or research roles expects
System Design
System Design: Ride-Sharing App (Uber / Lyft)
Designing a ride-sharing app is a rich system design problem that tests your ability to handle real-time location data, geospatial
System Design
System Design: Notification System (Push, Email, SMS)
A notification system is asked at almost every senior system design interview because it surfaces real architectural challenges: fanout at
System Design
System Design: Search Autocomplete (Google Typeahead)
Search autocomplete — the suggestions that appear as you type into Google, Amazon, or YouTube — is a deceptively interesting
AI/ML Interview Questions
Overfitting and Regularization: L1, L2, Dropout, and Early Stopping
Overfitting is the most common failure mode in machine learning. Every ML interview will test your ability to recognize it