Machine Operation Interview Questions

6,441 machine operation interview questions shared by candidates

ML design question involving ranking/recommendations Big data question about SQL 3 coding questions: First one is a variation on binary search. Second one is a graph traversal problem (think BFS). Last one involved implementing matrix addition and multiplication for sparse matrices.
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Machine Learning Engineer

Interviewed at Pinterest

3.6
Aug 8, 2022

ML design question involving ranking/recommendations Big data question about SQL 3 coding questions: First one is a variation on binary search. Second one is a graph traversal problem (think BFS). Last one involved implementing matrix addition and multiplication for sparse matrices.

They asked me to implement a sparse matrix from scratch, without relying on any existing matrix or linear algebra libraries. This required designing an efficient internal data structure to store only the non-zero elements, rather than allocating memory for the entire matrix. In addition to the core representation, I needed to implement both addition and multiplication operations, making sure they handled sparsity correctly, maintained good performance, and produced accurate results even when matrices had different sparsity patterns.
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Machine Learning Scientist

Interviewed at Pinterest

3.6
Dec 13, 2025

They asked me to implement a sparse matrix from scratch, without relying on any existing matrix or linear algebra libraries. This required designing an efficient internal data structure to store only the non-zero elements, rather than allocating memory for the entire matrix. In addition to the core representation, I needed to implement both addition and multiplication operations, making sure they handled sparsity correctly, maintained good performance, and produced accurate results even when matrices had different sparsity patterns.

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