In-Memory Music Analytics Service | Dataford Interview Questions

Design an in-memory music analytics service: add_song, play_song(userId, songId), print_analytics() listing songs by number of unique listeners.

Asked in the phone screen stage. Implement music_analytics(commands), where commands are arrays: ["add_song", songId], ["play_song", userId, songId], or ["print_analytics"]. Return one analytics snapshot for each print command. Each snapshot lists [songId, uniqueListenerCount] pairs, ordered by descending listener count, then ascending songId. Duplicate songs are ignored, and plays for unknown songs are ignored.

Example: adding s1, then playing it by u1 twice produces [["s1", 1]]. With s2 played by two users, the output is [["s2", 2], ["s1", 1]].

Constraints

1 <= commands.length <= 10^4
Each command is a valid add_song, play_song, or print_analytics command
Song IDs and user IDs are non-empty strings
There are at most 10^3 distinct songs and 10^4 distinct users
Analytics are ordered by descending unique listener count, then ascending song ID

Function Signature

def music_analytics(commands):

Your question is In-Memory Music Analytics Service. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Design an in-memory music analytics service: add_song, play_song(userId, songId), print_analytics() listing songs by number of unique listeners.

Example: adding s1, then playing it by u1 twice produces [["s1", 1]]. With s2 played by two users, the output is [["s2", 2], ["s1", 1]].

Constraints

1 <= commands.length <= 10^4
Each command is a valid add_song, play_song, or print_analytics command
Song IDs and user IDs are non-empty strings
There are at most 10^3 distinct songs and 10^4 distinct users
Analytics are ordered by descending unique listener count, then ascending song ID

Function Signature

def music_analytics(commands):

Your question is In-Memory Music Analytics Service. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.