Meeting Rooms Problem Minimum Rooms Required in DSA Python - Build from Scratch

Meeting Rooms Problem Minimum Rooms Required

📖 Scenario: You are organizing meetings in a company. Each meeting has a start time and an end time. You want to find out the minimum number of meeting rooms needed so that all meetings can happen without overlapping in the same room.

🎯 Goal: Build a program that calculates the minimum number of meeting rooms required given a list of meeting time intervals.

📋 What You'll Learn

Create a list called meetings with the exact intervals: [ (0, 30), (5, 10), (15, 20) ]

Create a variable called start_times that contains the start times of all meetings sorted in ascending order

Create a variable called end_times that contains the end times of all meetings sorted in ascending order

Use two pointers start_ptr and end_ptr to traverse start_times and end_times

Create variables used_rooms and max_rooms to track current and maximum rooms needed

Implement the logic to increase used_rooms when a meeting starts before the earliest meeting ends, else decrease used_rooms

Print the final max_rooms which is the minimum number of meeting rooms required

💡 Why This Matters

🌍 Real World

Scheduling meeting rooms efficiently is important in offices to avoid conflicts and maximize resource use.

💼 Career

This problem is common in software engineering interviews and helps develop skills in sorting, two-pointer technique, and interval management.

1

Create the list of meeting intervals

Create a list called meetings with these exact tuples: (0, 30), (5, 10), and (15, 20)

DSA Python

# Create the list of meetings with exact intervals
# Your code here

Hint

Use square brackets for the list and parentheses for each tuple.

2

Extract and sort start and end times

Create a list called start_times containing the start times of all meetings sorted in ascending order, and a list called end_times containing the end times of all meetings sorted in ascending order

DSA Python

meetings = [(0, 30), (5, 10), (15, 20)]
# Create start_times and end_times lists sorted ascending
# Your code here

Hint

Use list comprehensions to extract start and end times, then sort them.

3

Implement the logic to find minimum rooms

Create variables start_ptr and end_ptr set to 0, used_rooms set to 0, and max_rooms set to 0. Use a while loop to traverse start_times while start_ptr is less than the length of start_times. Inside the loop, if start_times[start_ptr] is less than end_times[end_ptr], increase used_rooms by 1 and move start_ptr forward. Else, decrease used_rooms by 1 and move end_ptr forward. Update max_rooms to be the maximum of itself and used_rooms in each iteration.

DSA Python

meetings = [(0, 30), (5, 10), (15, 20)]
start_times = sorted([meeting[0] for meeting in meetings])
end_times = sorted([meeting[1] for meeting in meetings])
# Initialize pointers and counters
# Your code here

Hint

Use two pointers to compare start and end times and track rooms used.

4

Print the minimum number of meeting rooms required

Print the variable max_rooms which holds the minimum number of meeting rooms required

DSA Python

meetings = [(0, 30), (5, 10), (15, 20)]
start_times = sorted([meeting[0] for meeting in meetings])
end_times = sorted([meeting[1] for meeting in meetings])

start_ptr = 0
end_ptr = 0
used_rooms = 0
max_rooms = 0

while start_ptr < len(start_times):
    if start_times[start_ptr] < end_times[end_ptr]:
        used_rooms += 1
        start_ptr += 1
        max_rooms = max(max_rooms, used_rooms)
    else:
        used_rooms -= 1
        end_ptr += 1

# Print the minimum number of rooms needed
# Your code here

Hint

Use print(max_rooms) to show the result.