// An online game requires a leaderboard to be created with capabilities mentioned below. Design the leaderboard keeping all data in-memory.

// 1. Upsert/Delete/Fetch user name/profile

// 2. Upsert/Fetch score for a given user

// 3. Fetch the rank for a user based on the score which the user has at any given point of time

// 4. Return the top k rank holders at a given point of time

// 5. Return all the users having a score “s”