Maximum Number of Events That Can Be Attended

MediumGreedyheap

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

Practice this as a mock interviewFree to start, no account needed

Problem

You are given a list of events, where events[i] = [startDay, endDay] means event i can be attended on any single day d with startDay <= d <= endDay (both ends inclusive). You can attend at most **one** event per day, and attending an event takes exactly one day of its window. Return the maximum number of distinct events you can attend. Aim for O(n log n) time, where n is the number of events.

Examples

Input: events = [[1,2],[2,3],[3,4]]
Output: 3
Attend event 0 on day 1, event 1 on day 2, and event 2 on day 3.
Input: events = [[1,2],[1,2],[1,2]]
Output: 2
Only days 1 and 2 are available, so at most two of the three identical events fit.

Constraints

  • 1 <= events.length <= 10^5
  • events[i].length == 2
  • 1 <= startDay <= endDay <= 10^5

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

More heap problems