Best Tracks Across Countries | Dataford Interview Questions

Given unsorted lists of tracks per country (Track: id, country, count, genre), implement getBestNTracksinACountry(String country, int n) and getBestNTracksGlobally(int n) summing counts across countries.

Asked in the Onsite - Coding stage. The interviewer preferred plain sorting over quickselect. Reported follow-up: What happens if we got these requests too often?

Contract

Use Python dictionaries with keys id, country, count, and genre. Each function receives tracks, country, and n; pass country=None for the global operation. Return up to n track IDs, ordered by descending summed count, then ascending ID for ties. The country operation only includes matching records; the global operation sums every country.

Constraints

1 <= len(tracks) <= 10^4
0 <= count <= 10^9
1 <= n <= 10^4
Each track contains string fields id, country, and genre, plus an integer count
Track IDs are compared lexicographically when summed counts tie

Function Signature

def getBestNTracksinACountry(tracks, country, n):

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Problem