add 1845

Author: rustykitty

1845-seat-reservation-manager.cpp

@@ -0,0 +1,39 @@
+/*
+1845. Seat Reservation Manager
+
+Submitted: December 7, 2024
+
+Runtime: 47 ms (beats 96.42%)
+Memory: 155.57 MB (beats 27.02%)
+*/
+
+class SeatManager {
+private:
+    const int capacity;
+    // priority queue uses reversed ordering for some reason
+    priority_queue<int, vector<int>, greater<int> > seats;
+public:
+    SeatManager(int n) : capacity(n) {
+        // all seats initially available
+        for (int i = 1; i <= n; ++i) seats.push(i);
+    }
+
+    int reserve() {
+        // lowest seat number
+        int seatNumber = seats.top();
+        seats.pop();
+        return seatNumber;
+    }
+    
+    void unreserve(int seatNumber) {
+        // seat is now available
+        seats.push(seatNumber);
+    }
+};
+
+/**
+ * Your SeatManager object will be instantiated and called as such:
+ * SeatManager* obj = new SeatManager(n);
+ * int param_1 = obj->reserve();
+ * obj->unreserve(seatNumber);
+ */