PPractick

The problem

A single conference room has n meeting requests, each with a start and an end time. Only one meeting can use the room at a time, and a meeting can start only strictly after the previous one ends (the room needs a moment to reset). What's the maximum number of meetings that can be held? This is interval scheduling, and the classic greedy is to always pick the meeting that finishes earliest among those that fit, because finishing early leaves the most room for the rest.

Example: start [1, 3, 0, 5, 8, 5], end [2, 4, 6, 7, 9, 9] → 4.

Function signature

int maxMeetings(const vector<int>& start, const vector<int>& end);

Test cases

Input (start, end)	Output	Explanation
([1, 3, 0, 5, 8, 5], [2, 4, 6, 7, 9, 9])	4	(1,2), (3,4), (5,7), (8,9)
([10, 12, 20], [20, 25, 30])	1	20 is not strictly after 20
([1, 2], [1, 2])	2	Instant meetings
([1, 1, 1], [2, 2, 2])	1	All overlap
([1], [5])	1

(Confirm: a meeting may start only when its start is strictly greater than the previous meeting's end.)

How interviewers phrase it

• "Given start and end times of N meetings, find the maximum number of meetings that can be accommodated in one room" (GeeksforGeeks "N meetings in one room"). It's the activity selection problem.

Clarifying questions to ask

1. Can a meeting start at the exact time the previous one ends? (Not here: strictly after.)
2. Should I return the count or the chosen meetings?
3. How are ties in end time handled? (Any order works for the count.)

Follow-ups to expect

1. "Why the earliest end time?"
2. "Why not the earliest start or the shortest meeting?"
3. "How do you output the meeting indices?"
4. "The minimum number of rooms for all meetings?"
5. "Complexity?"

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