252. Meeting Rooms

252_meeting_rooms/problem.md

@@ -0,0 +1 @@
+## 問題: [252. Meeting Rooms](https://neetcode.io/problems/meeting-schedule/question)

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: $O(nm)$

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: $O(1)$

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