Product Requirements Give a list of query suggestions based on user input (as a prefix) Suggestions ordered by some ranking score Non-product Requirements High performance, response should be quicker than user type speed, let’s say < 200ms Result accuracy and system availability are not strictly required Main Data Structure Trie is a data structure that fits prefix…

Product Requirements [Post] User can create a post (image + text (optional)) [Post] User can comment on a post [Post] User can like a post [Feed] User can get follow feed ordered by time (landing page) [Feed] User can get profile feed of another user ordered by time The above functionalities can…

Product Requirements P1: Create short URL with full URL as input. P1: Get/Redirect to full URL with short URL as input. P2: Short URL expiration time. Non-product Requirements P1: Performant — short URL should be as fast as full URL, which means look up and redirect time should be seamless. P1: Highly available —…

Calendar is important in my daily life. It frees part of my brain from remembering tedious scheduled tasks and makes it easier to manage my time. As an engineer who use google calendar heavily, I’m intereted of how such calendar system is built from zero and upgraded with more features…