Implement k-means from scratch

Last updated: September 25, 2025

Quick Overview

Write a clean implementation of logistic regression without using ML libraries.

Booking.com
Machine Learning
Machine Learning Engineer
Booking.com
September 25, 2025
Machine Learning Engineer
Technical Screen
Machine Learning
Medium

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2,515 solved


Write a clean implementation of logistic regression without using ML libraries.

This ML question from Booking.com's Technical Screen goes beyond textbook definitions. The interviewer wants to see how you reason about model selection, evaluation metrics, and the practical challenges of deploying ML in production.

What the Interviewer Expects
  • Explain the mathematical foundations with clarity
  • Discuss practical implementation considerations and hyperparameter tuning
  • Analyze the technique's strengths and weaknesses for different data types
  • Demonstrate understanding of evaluation methodology and metrics
  • Connect theory to real-world applications with concrete examples
Key Topics to Cover
Overfitting and underfitting
Ensemble methods (bagging, boosting, stacking)
Supervised vs unsupervised learning
Gradient descent and optimization
Feature importance and selection
How to Approach This
  1. Understand the bias-variance trade-off. High training accuracy but low test accuracy signals overfitting.
  2. Choose evaluation metrics carefully based on the problem. Accuracy alone is often insufficient.
  3. Feature engineering is often more impactful than model selection.
  4. Know when to use tree-based models (tabular data) vs neural networks (unstructured data).
  5. Handle class imbalance with SMOTE, class weights, or appropriate loss functions.
Possible Follow-up Questions
  • How would you explain this model's predictions to a non-technical stakeholder?
  • How would you detect and handle concept drift?
  • How would you handle a highly imbalanced dataset?
  • What are the computational costs of this approach at scale?
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Explore ML Interview Prep
Sample Answer
Core Concept: K-Means Clustering

K-Means is an unsupervised learning algorithm used to partition a dataset into K distinct clusters based on feature similarity. The core idea is to minimize the within-cluster variance, which can be m...

How It Works: Algorithmic Mechanism

The K-Means algorithm proceeds through the following steps:

  1. Initialization: Randomly select K points as initial centroids.
  2. Assignment Step: For each data point, assign it to the nearest ...

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