Software Engineer · Onsite · Coding

Pinterest — Software Engineer

Level: Mid-Level

Round: Onsite · Type: Coding · Difficulty: 7/10 · Duration: 60 min · Interviewer: Neutral

Topics: Graph Traversal, Sparse Matrix

Location: San Francisco Bay Area

Interview date: 2025-12-28

Summary

The onsite interview included questions about reconstructing a travel route from a list of tickets and implementing sparse matrix storage with addition and multiplication.

Details

The coding question I received focused on travel routes. I was given a list of travel tickets (city A to B) in the format [[A, B], [B, C] ...] and needed to output the complete travel itinerary, such as [A, B, C]. A key part was identifying the starting point myself.

I also had to implement storage, addition, and multiplication for sparse matrices.

My approach:

1. For the travel route, I used a graph data structure to represent the connections between cities.
2. For the sparse matrix, I explored different storage formats like coordinate lists and compressed row storage.

Key insights:

• Understanding graph traversal algorithms is critical for solving the travel route problem efficiently.
• Efficient sparse matrix operations require careful consideration of storage format and algorithm selection.