Software Engineer · Onsite · Coding, System Design

Roblox — Software Engineer ✅ Passed

Level: Senior-Level

Round: Onsite · Type: Coding, System Design · Difficulty: 6/10 · Duration: 180 min · Interviewer: Friendly

Topics: Algorithms, System Design

Location: San Francisco Bay Area

Interview date: 2025-12-31

Summary

This onsite interview consisted of a coding round and a system design round.

Details

I had an onsite interview at Roblox. The coding questions can be found in this platform. There were two follow-up questions, making a total of three coding questions. I was a bit rushed on the third question, but the interviewer was nice and let me finish and briefly discuss it.

The system design question seemed new.

One of the coding questions was: given a function call list, find the most frequent call trace. Determine which function was called the most. If there are ties, return the first one. The log format has start and end markers, such as:

`

main a b < b b < b < a a < a < main `

There were three levels of difficulty for this question:

• Level 1: If there are ties in the number of calls, return the function that appeared first.
• Level 2: If there are ties in the number of calls, return the function with the same stack depth that appeared first.
• Level 3: The function call list has thread IDs. For each thread ID, return the Level 2 result.