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253. Meeting Rooms II #21

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253. Meeting Rooms II #21

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問題

https://leetcode.com/problems/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
 

Constraints:
1 <= intervals.length <= 104
0 <= starti < endi <= 106

言語

Java

次に解く問題

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@katsukii katsukii changed the title 253 253. Meeting Rooms II Apr 20, 2025
Comment on lines +74 to +76
if (intervals == null || intervals.length == 0) {
return 0;
}
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intervals == null はともかく、空ならば特に問題なく0が返りますか?

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はい、空配列の場合 intervals.length == 0 がtrueとなります。

- イベント変換: 各会議の開始時刻と終了時刻をそれぞれイベントとして配列に変換する
- 開始イベント: +1 カウント(会議室使用開始)
- 終了イベント: -1 カウント(会議室リリース)
- イベントソート: 両イベント配列を 2D 配列として一つの配列にマージして時刻順(昇順)にソートする。同時刻にイベントが複数存在する場合、終了イベント(-1)を優先する
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時刻ごとにいくつ増えるか減るか、と思うこともできますね。

全体的に問題ないかと思います。

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ありがとうございます。

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