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Compute minimum meeting rooms on circular day

Last updated: Mar 29, 2026

Quick Overview

This question evaluates a candidate's ability to reason about interval scheduling, circular time wrap-around, and resource allocation for overlapping events.

  • easy
  • Google
  • Coding & Algorithms
  • Software Engineer

Compute minimum meeting rooms on circular day

Company: Google

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: easy

Interview Round: Onsite

## Problem You are given a list of meetings scheduled within a 24-hour day. Time is **cyclic**: after `23:59` the next minute is `00:00`. Each meeting is represented as `(start, end)` where `start` and `end` are times within the day (e.g., minutes from `0` to `1439`, or strings `HH:MM` you can convert to minutes). - A meeting occupies the half-open interval **[start, end)**. - If `end > start`, the meeting occurs within the same day. - If `end <= start`, the meeting **wraps past midnight** (e.g., `23:00 -> 01:00`). Two meetings overlap if their occupied time intervals intersect (considering wrap-around). ### Task Return the **minimum number of conference rooms** required so that no overlapping meetings share a room. ### Examples - Meetings: `[(60, 120), (90, 150)]` → overlaps → answer `2`. - Meetings: `[(1380, 60), (30, 90)]` where `(1380, 60)` wraps midnight → overlaps with `(30, 90)` → answer `2`. ### Constraints - `1 <= n <= 2 * 10^5` - Times are within one day (0..1439) or equivalent. ### Follow-up If the number of meetings is extremely large, how would you optimize the approach (time and/or space), given the timeline is only one day and thus bounded?

Quick Answer: This question evaluates a candidate's ability to reason about interval scheduling, circular time wrap-around, and resource allocation for overlapping events.

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Google
Jan 4, 2026, 12:00 AM
Software Engineer
Onsite
Coding & Algorithms
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Problem

You are given a list of meetings scheduled within a 24-hour day. Time is cyclic: after 23:59 the next minute is 00:00.

Each meeting is represented as (start, end) where start and end are times within the day (e.g., minutes from 0 to 1439, or strings HH:MM you can convert to minutes).

  • A meeting occupies the half-open interval [start, end) .
  • If end > start , the meeting occurs within the same day.
  • If end <= start , the meeting wraps past midnight (e.g., 23:00 -> 01:00 ).

Two meetings overlap if their occupied time intervals intersect (considering wrap-around).

Task

Return the minimum number of conference rooms required so that no overlapping meetings share a room.

Examples

  • Meetings: [(60, 120), (90, 150)] → overlaps → answer 2 .
  • Meetings: [(1380, 60), (30, 90)] where (1380, 60) wraps midnight → overlaps with (30, 90) → answer 2 .

Constraints

  • 1 <= n <= 2 * 10^5
  • Times are within one day (0..1439) or equivalent.

Follow-up

If the number of meetings is extremely large, how would you optimize the approach (time and/or space), given the timeline is only one day and thus bounded?

Submit Your Answer to Earn 20XP

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