Palo Alto Networks

Role: Senior Staff Engineer (modified to Senior Backend Engineer)

College: Not Specified

Interview Date: January 2022

Interview Type: Full-Time

Result: Neither selected nor rejected (mental torture), implied withdrawal/rejection due to prolonged process.

Difficulty: Hard

Rounds: Online Test + 4 Interview Rounds (iterative process)

Topics Asked: Data Structures, Algorithms, Project Discussions, High-Level Design, Low-Level Design

Experience:

An anonymous candidate on LeetCode Discuss shared a challenging and prolonged interview experience for a Senior Staff Engineer role at Palo Alto Networks in January 2022.

Online Test: The candidate scored well on the initial online test, which led to further interview rounds.

Round 1 (DSA + Project Discussion): This round focused on Data Structures and Algorithms, along with discussions about the candidate's projects. The interviewer expected a more optimal answer for a coding problem and surprisingly argued that the time complexity of `PriorityQueue poll()` operation was O(n) instead of the standard O(logn).

Round 2 (HLD + LLD + Project Discussion): This round involved a discussion around the High-Level Design and Low-Level Design of an Amazon-like e-commerce system, with a deep dive into a particular component. This round reportedly went well.

After these rounds, the recruiter informed the candidate that despite a high score on the online test, the feedback from the initial interview rounds was "not very good." The recruiter also mentioned that other interviewed candidates were also being rejected and scheduled further rounds for a "final verdict." The position was then modified from "Staff Engineer" to "Senior Backend Engineer."

Round 3 (DSA): This round was purely focused on Data Structures and Algorithms, given the feedback from Round 1. The candidate performed "really really well," answering two questions in 30 minutes with optimal solutions.

Round 4 (Hiring Manager): After further delays, a final round with the hiring manager was scheduled. This round was described as "okay," where the candidate answered some questions but not others, and was asked about the Low-Level Design of a snake game.

The candidate described the overall process as "mental torture" due to the prolonged nature, lack of timely feedback, and the need to repeatedly interview despite having another offer with a looming deadline. The final outcome was not explicitly stated as selected or rejected, implying the candidate likely withdrew or was not offered due to the extended process.