Meeting Rooms II in Java: Explanation & Practice

Problem summary

Given an array of meeting time intervals, find the minimum number of conference rooms required. Use min-heap to track end times.

Starter code

public class Main {
    public static void main(String[] args) {
        int[][] intervals = {{0,30},{5,10},{15,20}};
        
        // Sort by start time
        // Min-heap tracks earliest ending meeting
        // If new meeting starts after earliest end, reuse room
        // Print: Rooms: 2
    }
}

Expected output and test cases

• [[0,30],[5,10],[15,20]]

  Rooms: 2

• [[7,10],[2,4]] → no overlap

  Rooms: 1

• All overlap → 3 rooms

  Rooms: 3

Hints

1. Sort meetings by start time
2. Min-heap tracks end times of ongoing meetings
3. If new meeting starts after heap top, reuse room (poll and add new end)
4. Otherwise, need new room (just add new end)

Related Data Structures & Algorithms exercises

• Practice Top K Frequent Elements in Java
• Practice Find Median from Data Stream in Java

Practice all Data Structures & Algorithms exercises · Run this idea in the Java compiler