Untitled

import java.util.*;

class Interval {
    int start;
    int end;

    Interval(int start, int end) {
        this.start = start;
        this.end = end;
    }
}

public class Solution {
    public int minMeetingRooms(List<Interval> intervals) {
        if (intervals == null || intervals.isEmpty()) {
            return 0; // No intervals, no rooms needed
        }

        // Separate start and end times into two arrays
        int n = intervals.size();
        int[] startTimes = new int[n];
        int[] endTimes = new int[n];

        for (int i = 0; i < n; i++) {
            startTimes[i] = intervals.get(i).start;
            endTimes[i] = intervals.get(i).end;
        }

        // Sort both arrays
        Arrays.sort(startTimes);
        Arrays.sort(endTimes);

        int count = 0; // Current number of meeting rooms needed
        int maxRooms = 0; // Maximum number of rooms needed
        int i = 0, j = 0;

        // Use two pointers to traverse the start and end times
        while (i < n) {
            // If a meeting is starting, increment count
            if (startTimes[i] < endTimes[j]) {
                count++;
                maxRooms = Math.max(maxRooms, count);
                i++;
            }
            // If a meeting is ending, decrement count
            else {
                count--;
                j++;
            }
        }

        return maxRooms; // Return the maximum number of rooms needed
    }

    public static void main(String[] args) {
        List<Interval> intervals1 = Arrays.asList(
            new Interval(0, 40),
            new Interval(5, 10),
            new Interval(15, 20)
        );
        Solution solution = new Solution();
        System.out.println("Output 1: " + solution.minMeetingRooms(intervals1)); // Output: 2

        List<Interval> intervals2 = Arrays.asList(
            new Interval(4, 9)
        );
        System.out.println("Output 2: " + solution.minMeetingRooms(intervals2)); // Output: 1

        List<Interval> intervals3 = Arrays.asList(
            new Interval(0, 8),
            new Interval(8, 10)
        );
        System.out.println("Output 3: " + solution.minMeetingRooms(intervals3)); // Output: 1
    }
}