Created
July 22, 2017 04:34
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Plan to study Meeting room II - Java code
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public int minMeetingRooms(Interval[] intervals) { | |
if (intervals == null || intervals.length == 0) | |
return 0; | |
// Sort the intervals by start time | |
Arrays.sort(intervals, new Comparator<Interval>() { | |
public int compare(Interval a, Interval b) { return a.start - b.start; } | |
}); | |
// Use a min heap to track the minimum end time of merged intervals | |
PriorityQueue<Interval> heap = new PriorityQueue<Interval>(intervals.length, new Comparator<Interval>() { | |
public int compare(Interval a, Interval b) { return a.end - b.end; } | |
}); | |
// start with the first meeting, put it to a meeting room | |
heap.offer(intervals[0]); | |
for (int i = 1; i < intervals.length; i++) { | |
// get the meeting room that finishes earliest | |
Interval interval = heap.poll(); | |
if (intervals[i].start >= interval.end) { | |
// if the current meeting starts right after | |
// there's no need for a new room, merge the interval | |
interval.end = intervals[i].end; | |
} else { | |
// otherwise, this meeting needs a new room | |
heap.offer(intervals[i]); | |
} | |
// don't forget to put the meeting room back | |
heap.offer(interval); | |
} | |
return heap.size(); | |
} |
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