Problem

Given an array of meeting time intervals intervals where intervals[i] = [starti, endi], return the minimum number of conference rooms required.

Example 1:

Input: intervals = [[0,30],[5,10],[15,20]]
Output: 2

Example 2:

Input: intervals = [[7,10],[2,4]]
Output: 1

Constraints:

• 1 <= intervals.length <= 104
• 0 <= starti < endi <= 106

Java Solution

class Solution {
    public int minMeetingRooms(int[][] intervals) {
        int[] starts = new int[intervals.length];
        int[] ends = new int[intervals.length];
        for (int i = 0; i < intervals.length; i++) {
            starts[i] = intervals[i][0];
            ends[i] = intervals[i][1];
        }
        Arrays.sort(starts);
        Arrays.sort(ends);
        int room = 0, endIdx = 0;
        for (int i = 0; i < starts.length; i++) {
            if (starts[i] < ends[endIdx]) {
                room++;
            } else {
                endIdx++;
            }
        }
        return room;
    }
}