From 528d2350aa5fb55ed4cd44898ef7b92bdaba9bbc Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Fri, 27 Sep 2024 21:38:00 +0200
Subject: [PATCH] =?UTF-8?q?cs:=20add=20=C2=AB729.=20My=20Calendar=20I?=
 =?UTF-8?q?=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 cs/my-calendar-i.cs | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 cs/my-calendar-i.cs

diff --git a/cs/my-calendar-i.cs b/cs/my-calendar-i.cs
new file mode 100644
index 0000000..ad48b2c
--- /dev/null
+++ b/cs/my-calendar-i.cs
@@ -0,0 +1,41 @@
+public class MyCalendar {
+    private record Meeting(int Start, int End) {
+        public bool Has(int x) => x > Start && x < End;
+
+        public static bool operator <(Meeting a, Meeting b) => a.Start < b.Start;
+        public static bool operator >(Meeting a, Meeting b) => a.Start > b.Start;
+    }
+
+    private static bool Overlaps(Meeting a, Meeting b)
+        => a == b || a.Has(b.Start) || a.Has(b.End) || b.Has(a.Start) || b.Has(a.End);
+
+    private List<Meeting> meetings = [];
+
+    public MyCalendar() { }
+
+    public bool Book(int start, int end) {
+        meetings.Add(new Meeting(start, end));
+
+        var it = meetings.Count - 1;
+
+        for (
+            int i = meetings.Count - 1;
+            i > 0 && meetings[i - 1] > meetings[i];
+            --i, --it
+        ) {
+            if (Overlaps(meetings[i], meetings[i - 1])) {
+                meetings.RemoveAt(it);
+                return false;
+            }
+
+            (meetings[i], meetings[i - 1]) = (meetings[i - 1], meetings[i]);
+        }
+
+        if (it > 0 && Overlaps(meetings[it], meetings[it - 1])) {
+            meetings.RemoveAt(it);
+            return false;
+        }
+
+        return true;
+    }
+}