From 163aeafd47af62f43a10439d4e51c8c3814b664e Mon Sep 17 00:00:00 2001
From: SquidSpirit <squid@squidspirit.com>
Date: Sat, 20 Sep 2025 02:29:27 +0800
Subject: [PATCH] feat: 1845_seat_reservation_manager

---
 1845_seat_reservation_manager/Cargo.lock |  7 ++++++
 1845_seat_reservation_manager/Cargo.toml |  6 ++++++
 1845_seat_reservation_manager/src/lib.rs | 27 ++++++++++++++++++++++++
 3 files changed, 40 insertions(+)
 create mode 100644 1845_seat_reservation_manager/Cargo.lock
 create mode 100644 1845_seat_reservation_manager/Cargo.toml
 create mode 100644 1845_seat_reservation_manager/src/lib.rs

diff --git a/1845_seat_reservation_manager/Cargo.lock b/1845_seat_reservation_manager/Cargo.lock
new file mode 100644
index 0000000..147ff9b
--- /dev/null
+++ b/1845_seat_reservation_manager/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "seat_reservation_manager"
+version = "0.1.0"
diff --git a/1845_seat_reservation_manager/Cargo.toml b/1845_seat_reservation_manager/Cargo.toml
new file mode 100644
index 0000000..8950a40
--- /dev/null
+++ b/1845_seat_reservation_manager/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "seat_reservation_manager"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/1845_seat_reservation_manager/src/lib.rs b/1845_seat_reservation_manager/src/lib.rs
new file mode 100644
index 0000000..74bad0f
--- /dev/null
+++ b/1845_seat_reservation_manager/src/lib.rs
@@ -0,0 +1,27 @@
+use std::{cmp::Reverse, collections::BinaryHeap};
+
+pub struct SeatManager {
+    unreserved_seats: BinaryHeap<Reverse<i32>>,
+}
+
+impl SeatManager {
+    pub fn new(n: i32) -> Self {
+        Self {
+            unreserved_seats: BinaryHeap::from_iter((0..n).map(|i| Reverse(i))),
+        }
+    }
+
+    pub fn reserve(&mut self) -> i32 {
+        if let Some(Reverse(smallest_available_seat)) = self.unreserved_seats.peek() {
+            let result = *smallest_available_seat + 1;
+            self.unreserved_seats.pop();
+            result
+        } else {
+            -1
+        }
+    }
+
+    pub fn unreserve(&mut self, seat: i32) {
+        self.unreserved_seats.push(Reverse(seat - 1));
+    }
+}