Meeting Rooms II

Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), find the minimum number of conference rooms required.

Example 1:

```Input: [[0, 30],[5, 10],[15, 20]]
Output: 2```
Example 2:

```Input: [[7,10],[2,4]]
Output: 1```
NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

Solution:

```class Solution {
public int minMeetingRooms(int[][] intervals) {
if (intervals == null || intervals.length == 0) return 0;
Arrays.sort(intervals, (a, b) -> { return Integer.compare(a[0], b[0]); });
PriorityQueue<int[]> pq = new PriorityQueue<>((a, b) -> { return Integer.compare(a[1], b[1]); });
pq.offer(intervals[0]);
int i = 1;
while (i < intervals.length) {
int[] lastInterval = pq.poll();
int[] curInterval = intervals[i];
if (curInterval[0] >= lastInterval[1]) {
lastInterval[1] = Math.max(lastInterval[1], curInterval[1]);
lastInterval[0] = Math.min(lastInterval[0], curInterval[0]);
} else {
pq.offer(curInterval);
}
pq.offer(lastInterval);
i ++;
}
return pq.size();
}
}```