mediumDSA

How do you find the minimum number of meeting rooms required?

Q: How do you find the minimum number of meeting rooms required?

**Intuition.** A new room is only needed when a meeting starts before all earlier ones have ended. Sort meetings by start time and track ongoing end times in a **min-heap**: for each meeting, if the earliest end is ≤ this start, that room is free (reuse it); otherwise allocate a new room. The peak heap size is the answer. overlapping intervals → peak concurrency = rooms (here 2) [0

381 views

Understand the problem

Explain the meeting-rooms problem.

intervalssortingheap

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Stuck? AI Nudge Available

Get a conceptual hint to guide your logic without spoiling the final implementation.

Study the solution

The solution is waiting

Give it an honest attempt first — then compare your thinking with the full walkthrough.

Read the code

Sort + min-heap of end times

Run Playground

import heapq

def min_meeting_rooms(intervals):
    if not intervals:
        return 0
    intervals.sort(key=lambda x: x[0])    # by start
    heap = []                             # end times of ongoing meetings
    for start, end in intervals:
        if heap and heap[0] <= start:
            heapq.heappop(heap)           # a room freed up — reuse it
        heapq.heappush(heap, end)
    return len(heap)


# --- demo ---
print(min_meeting_rooms([[0, 30], [5, 10], [15, 20]]))   # 2

Join the discussion

Discussion (0)

No responses yet. Be the first to share what you think.

How do you solve the container with most water problem?

How do you solve the coin change problem?