Implement decision tree from scratch

Last updated: May 12, 2026

Quick Overview

Write a clean implementation of k-means without using ML libraries.

Expedia
Machine Learning
Machine Learning Engineer
Expedia
May 12, 2026
Machine Learning Engineer
Onsite
Machine Learning
Medium

42

1

2,123 solved


Write a clean implementation of k-means without using ML libraries.

Machine learning questions at Expedia test both theoretical understanding and practical experience. This Onsite question evaluates your knowledge of ML fundamentals and your ability to apply them to real-world problems.

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
Bias-variance trade-off
Gradient descent and optimization
Regularization techniques (L1, L2, dropout)
Overfitting and underfitting
Supervised vs unsupervised learning
Cross-validation and model evaluation
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 ensure reproducibility in your ML pipeline?
  • What are the computational costs of this approach at scale?
  • How would you detect and handle concept drift?
  • How would you explain this model's predictions to a non-technical stakeholder?
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Sample Answer
Core Concept Explanation

Start with a clear, intuitive explanation of the concept. Use analogies when helpful. Then go deeper into the mathematical foundations: **Key Intuiti...

Practical Application

**When to use**: Describe the scenarios where this technique is most effective. What data characteristics favor it? **When NOT to use**: Common pitfa...


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