feat: 1845_seat_reservation_manager

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"

1845_seat_reservation_manager/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "seat_reservation_manager"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

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));
+    }
+}