Rippling Interview question

Round 1

Questions: Design a system to track song plays and generate analytics based on the number of unique listeners per song. Implement the SongAnalytics class with the following methods:

1. SongAnalytics()
   Initializes the system.

2. int add_song(string name)
   Adds a song to the system, assigns it a unique auto-incrementing ID starting from 1, and returns the assigned ID.

3. void play_song(int song_id, int user_id)
   Records a play event for a song by a user.

   • If song_id does not exist, output: Error: Song ID <song_id> does not exist. (replace <song_id> with the invalid ID).
   • Each user is counted once per song, even if they play it multiple times.

4. void print_analytics()
   Prints a summary of all songs sorted by the number of unique listeners in descending order.

   • If two songs have the same number of unique listeners, sort them lexicographically by name in ascending order.
   • Each line in the output should follow the format: <song_name> (<count> unique listeners).

Example:

Input:
add_song("Song A") → returns 1  
add_song("Song B") → returns 2  
add_song("Song C") → returns 3  
play_song(1, 1)  
play_song(1, 2)  
play_song(2, 1)  
play_song(3, 3)  
play_song(3, 3)  
print_analytics()  

Output:
Song A (2 unique listeners)  
Song B (1 unique listeners)  
Song C (1 unique listeners)  

Explanation:

• "Song A" has 2 unique listeners.
• "Song B" and "Song C" both have 1 unique listener. They are sorted lexicographically by name ("Song B" before "Song C").

Note:

• Ensure the solution efficiently handles multiple calls to play_song and print_analytics.