> For the complete documentation index, see [llms.txt](https://heunnajo.gitbook.io/algorithms-problem-solving-skills/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://heunnajo.gitbook.io/algorithms-problem-solving-skills/algorithm-problems/meetingroom2-1.md).

# MeetingRoom2

**알고리즘**\
1\. sorting by start time\
2\. create a PriorityQueue by end time.\
3\. before.end <= after.start : 합치기\
&#x20;   before.end > after.start : 회의실 1개 추가 필요.\
4\. 최종적으로 heap의 크기가 정답(필요한 미팅룸 갯수)가 된다.

**필요한 자료구조 : Heap**

: BST 로 구성된다. 시간복잡도는 nlogn\
end시간으로 오름차순으로 MinHeap을 구성하게 되면 아래와 같다.

![](/files/-MN6dSPh4oVv4i59_0le)

```java
package java_basic;

import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Queue;

class Interval {
	int start;
	int end;
	Interval() {start = 0; end = 0;}
	Interval(int s, int e) {start = s; end = e;}
}
public class MeetingRoom2 {

	public static void main(String[] args) {
		Interval in1 = new Interval(5,10);
		Interval in2 = new Interval(0,30);
		Interval in3 = new Interval(15,25);

		Interval[] intervals = {in1,in2,in3};
		
		MeetingRoom2 MR2 = new MeetingRoom2();
		/*int result = MR2.solve(intervals);
		
		System.out.println("필요한 미팅룸 갯수 :" + result);*/
		System.out.println(MR2.solve(intervals));
	}

	public int solve(Interval[] intervals) {
		if(intervals == null || intervals.length == 0) return 0;
		
		
		//알고리즘 구현.
		//1. start time으로 정렬. 받은 intervals가 배열이니까
		Arrays.sort(intervals,(a,b)->(a.start-b.start));
		
		//2. end time으로 정렬, 우선순위큐 MinHeap.
		Queue<Interval> minHeap = new PriorityQueue<Interval>(intervals.length,Comp);
		
		minHeap.offer(intervals[0]);
		for(int i=1; i <= intervals.length;i++) {
			Interval interval = minHeap.poll();//else인 경우 두개가 필요한데 poll하면 어떻함.
			if(interval.end <= intervals[i].start) {//하나로 합친다! 
				interval.end = Math.max(interval.end, intervals[i].end);
			} else {//미팅룸 하나 더 생성(힙에 노드 하나 추가) 
				minHeap.offer(intervals[i]);
			}
			minHeap.offer(interval);
		}
		return minHeap.size();
	}
	Comparator Comp = new Comparator<Interval>() {
		public int compare(Interval a, Interval b) {
			return a.end - b.end;
		}
	};
}

```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://heunnajo.gitbook.io/algorithms-problem-solving-skills/algorithm-problems/meetingroom2-1.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.