Perplexity Software Engineer Interview Experience — A 4-Part 'Todo List for AI' Coding Round

Perplexity·Software Engineer·Apr 2026
Technical ScreenRejectedhard

I applied through LinkedIn. The first round was with a recruiter who just asked some basic info, then scheduled a coding round. It had to be done in Python.

The coding round question was the "implement todo list for AI" one that's already been posted on the forum. There were 4 parts total. I only got through the first two parts before running out of time. The second part was a pain because every task needed to track parent and child dependencies (dependent vs dependency), and you had to write a helper method like a cascade failure (when a task gets marked failed, everything that depends on it has to fail too). I wrote it with DFS, and all the test cases passed except for one big test case at the end where my code timed out. I never fixed that one test case by the time the interview ended. The test case had its own Python file, but I was pretty nervous during the interview so I read through it slowly and didn't fully understand how the test case was constructed. Maybe there were a few hundred tasks depending on each other?

Overall the format of this question was a lot like an OA — a long set of instructions, and each part had its own test cases. The interviewer just had me start coding right away, barely any small talk. I'm guessing they already know most people can't finish this question anyway.

Got a message the next day saying I was rejected.

Published

Curated and edited by PracHub

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Interview at a glance

Company
Perplexity
Role
Software Engineer
Rounds
Technical Screen
Outcome
Rejected
Difficulty
hard
Interview date
Apr 2026
Questions from this interview
1 question

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