Meeting Rooms II

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

Solution

class Solution {

public int minMeetingRooms(int[][] intervals) {

// Sort intervals by start

Arrays.sort(intervals, Comparator.comparing((int[] intrvl) -> intrvl[0]));

int count=0;

PriorityQueue<Integer> heap = new PriorityQueue<>();

for(int[] intrvl : intervals) {

if(heap.isEmpty()) {

count++;

heap.add(intrvl[1]);

} else {

if(intrvl[0] >= heap.peek()) {

heap.poll();

} else {

count++;

}

heap.add(intrvl[1]);

}

}

return count;

}

}