Compute minutes since last train departure

Q: Compute minutes since last train departure

This question evaluates time arithmetic and handling of cyclic day-wrap boundary conditions along with parsing and comparison of timestamp lists, reflecting skills in correct edge-case reasoning and efficient data processing.

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Question

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You are given a daily train timetable as a list of departure times (24-hour format HH:MM). Given the current time (also HH:MM), find the most recent departure time that is not later than the current time, and return how many minutes have elapsed since that departure.

If there is no departure earlier than or equal to the current time on the same day, treat it as wrapping to the previous day’s last departure.

Input

departures : list of strings, each in HH:MM (not necessarily sorted)
now : string in HH:MM

Output

Return:

last_departure : the departure time (as HH:MM ) that most recently occurred relative to now
minutes_ago : the number of minutes between last_departure and now

Example

departures = ["01:10", "03:20", "05:20"] , now = "03:40"
last_departure = "03:20" , minutes_ago = 20

Constraints (assume typical interview constraints)

1 <= len(departures) <= 10^5
Times are valid and within a 24-hour day.

Compute minutes since last train departure

Quick Overview

Input

Output

Example

Constraints (assume typical interview constraints)

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