From 10557d39dd94c9b8f07b03666511d153af3abd23 Mon Sep 17 00:00:00 2001
From: Hiro Funatsuka <hiro.funatsuka@gmail.com>
Date: Sat, 2 May 2026 21:29:42 +0900
Subject: [PATCH] Solve meeting rooms

---
 252_meeting_rooms/.DS_Store  | Bin 0 -> 6148 bytes
 252_meeting_rooms/problem.md |   1 +
 252_meeting_rooms/step1.md   |  29 +++++++++++++++++++++++++++++
 252_meeting_rooms/step2.md   |  25 +++++++++++++++++++++++++
 252_meeting_rooms/step3.md   |  25 +++++++++++++++++++++++++
 5 files changed, 80 insertions(+)
 create mode 100644 252_meeting_rooms/.DS_Store
 create mode 100644 252_meeting_rooms/problem.md
 create mode 100644 252_meeting_rooms/step1.md
 create mode 100644 252_meeting_rooms/step2.md
 create mode 100644 252_meeting_rooms/step3.md

diff --git a/252_meeting_rooms/.DS_Store b/252_meeting_rooms/.DS_Store
new file mode 100644
index 0000000000000000000000000000000000000000..5008ddfcf53c02e82d7eee2e57c38e5672ef89f6
GIT binary patch
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diff --git a/252_meeting_rooms/problem.md b/252_meeting_rooms/problem.md
new file mode 100644
index 0000000..1072947
--- /dev/null
+++ b/252_meeting_rooms/problem.md
@@ -0,0 +1 @@
+## 問題: [252. Meeting Rooms](https://neetcode.io/problems/meeting-schedule/question)
diff --git a/252_meeting_rooms/step1.md b/252_meeting_rooms/step1.md
new file mode 100644
index 0000000..0a3f027
--- /dev/null
+++ b/252_meeting_rooms/step1.md
@@ -0,0 +1,29 @@
+# Step 1
+
+- それぞれのinterval objectのstartからend値をsetに追加していく
+- すでにsetに入っていたらFalseを返す
+- ぜんぶ追加できてループを抜けたらTrueを返す
+
+```python
+"""
+Definition of Interval:
+class Interval(object):
+    def __init__(self, start, end):
+        self.start = start
+        self.end = end
+"""
+
+class Solution:
+    def canAttendMeetings(self, intervals: List[Interval]) -> bool:
+        times = set()
+        for interval in intervals:
+            for i in range(interval.start, interval.end):
+                if i in times:
+                    return False
+                times.add(i)
+        return True
+```
+
+時間計算量: $O(nm)$
+
+空間計算量: $O(nm)$
diff --git a/252_meeting_rooms/step2.md b/252_meeting_rooms/step2.md
new file mode 100644
index 0000000..c3cf678
--- /dev/null
+++ b/252_meeting_rooms/step2.md
@@ -0,0 +1,25 @@
+# Step 2
+
+- 開始時間でintervalをソートし、intervalの開始時間が前のintervalの終了時間より早い場合はFalseを返す
+
+```python
+"""
+Definition of Interval:
+class Interval(object):
+    def __init__(self, start, end):
+        self.start = start
+        self.end = end
+"""
+
+class Solution:
+    def canAttendMeetings(self, intervals: List[Interval]) -> bool:
+        intervals.sort(key=lambda i: i.start)
+        for i in range(1, len(intervals)):
+            if intervals[i].start < intervals[i - 1].end:
+                return False
+        return True
+```
+
+時間計算量: $O(n\log n)$
+
+空間計算量: $O(1)$
diff --git a/252_meeting_rooms/step3.md b/252_meeting_rooms/step3.md
new file mode 100644
index 0000000..47cd58d
--- /dev/null
+++ b/252_meeting_rooms/step3.md
@@ -0,0 +1,25 @@
+# Step 3
+
+```python
+"""
+Definition of Interval:
+class Interval(object):
+    def __init__(self, start, end):
+        self.start = start
+        self.end = end
+"""
+
+class Solution:
+    def canAttendMeetings(self, intervals: List[Interval]) -> bool:
+        intervals.sort(key=lambda i: i.start)
+        for i in range(1, len(intervals)):
+            if intervals[i - 1].end > intervals[i].start:
+                return False
+        return True
+```
+
+1回目: 1分　15秒
+
+2回目: 0分　50秒
+
+3回目: 0分　53秒