Syllabus Lesson 3 of 141 · The blind start
The blind start

Baseline 2: a time for everyone

AI off This is a baseline exam. The tutor is switched off and there are no hints. Work alone, the way you would with no assistant open. Nothing here is a trick: every rule is written in the exercise. Your result is only compared with your own final exam at the end of the course.

A scheduling service finds the next time a whole team can meet. Each person's calendar lives in a separate store, and every entry fetched costs a network call, so the service is billed by entries read. Teams are large and calendars go back years.

A small example

from creative.budget import Tape
cals = [[(0, 30), (60, 90)], [(10, 40)], []]
earliest_slot([Tape(c) for c in cals], 0, 15)   # -> 40  (free from 40 to 60)
earliest_slot([Tape(c) for c in cals], 0, 20)   # -> 40  (40 + 20 = 60: touching is fine)
earliest_slot([Tape(c) for c in cals], 0, 25)   # -> 90
Your turn

Write earliest_slot(calendars, after, length). calendars is a list of Tapes, one per person. Each holds that person's meetings as (start, end) minute pairs, sorted by start; a meeting is busy from start up to but not including end, and one person's meetings never overlap (they may touch). Return the earliest minute t >= after such that nobody is busy anywhere in [t, t + length). Everyone is free after their last meeting, so there is always an answer.
Budget: there are 50 people with 2,000 meetings each (100,000 entries), and after is usually months into the data. One search may read at most 10,000 entries in total. len() of a Tape is free. A Tape behaves like a read-only list (indexing, slicing and looping all work), and every entry it hands you counts as one read.

AI off: no tutor, hints or worked solution on this one. Your own thinking only.

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