The process started with an internal referral. After a brief initial chat, I was invited to a technical phone screen, followed by an on-site interview.

The on-site interview consisted of:

• Two coding rounds
• Two system design rounds
• One behavioral round

The coding rounds featured one medium and one hard LeetCode question, both tagged for Meta. The system design interviewer was excellent, asking many creative follow-up questions that went beyond the typical "What sort of caching mechanism would you build for this?"

I had a good grasp of system design thanks to practice on standard channels, including one mock interview on interviewing.io and five to six system design mocks on Prepfully.

My recommendation: Keep practicing LeetCode hard questions and schedule a mock interview for each type on Prepfully. Importantly, DO NOT underestimate the behavioral interview, as it contributed as much to my leveling as the system design rounds did.

Parse a phone number using code.

Given a sorted array and a target number, return the frequency of the target in the array in O(log N) time.