Code RoomDeduplicate contacts by email
MediumPrep Room Coding #5039

Deduplicate contacts by email

CodingAlgorithms & data structuresMid–Senior~9 min

Given `contacts` with columns `email` and `name`, where later rows are more recent, keep only the LAST row for each `email`. Return `email` and `name`, sorted by `email` ascending.

Implement
latest_per_email(contacts: dataframe) → dataframe
Examples
in[{"__df__":[{"name":"Ann","email":"a@x.com"},{"name":"Bob","email":"b@x.com"},{"name":"Ann","email":"a@x.com"},{"name":"Cy","email":"c@x.com"},{"name":"Bobby","email":"b@x.com"}]}]out[{"name":"Ann","email":"a@x.com"},{"name":"Bobby","email":"b@x.com"},{"name":"Cy","email":"c@x.com"}]
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

0:00 of about 9 min
InputExpectedGot
[{"__df__":[{"name":"Ann","email":"a@x.com"},{"name":"Bob","email":"b@x.com"},{"name":"Ann","email":"a@x.com"},{"name":"Cy","email":"c@x.com"},{"name":"Bobby","email":"b@x.com"}]}][{"name":"Ann","email":"a@x.com"},{"name":"Bobby","email":"b@x.com"},{"name":"Cy","email":"c@x.com"}]not run yetsample