79 lines
2.8 KiB
C++
79 lines
2.8 KiB
C++
// Source : https://leetcode.com/problems/seat-reservation-manager/
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// Author : Hao Chen
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// Date : 2021-05-03
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/*****************************************************************************************************
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*
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* Design a system that manages the reservation state of n seats that are numbered from 1 to n.
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*
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* Implement the SeatManager class:
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*
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* SeatManager(int n) Initializes a SeatManager object that will manage n seats numbered from
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* 1 to n. All seats are initially available.
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* int reserve() Fetches the smallest-numbered unreserved seat, reserves it, and returns its
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* number.
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* void unreserve(int seatNumber) Unreserves the seat with the given seatNumber.
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*
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* Example 1:
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*
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* Input
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* ["SeatManager", "reserve", "reserve", "unreserve", "reserve", "reserve", "reserve", "reserve",
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* "unreserve"]
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* [[5], [], [], [2], [], [], [], [], [5]]
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* Output
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* [null, 1, 2, null, 2, 3, 4, 5, null]
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*
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* Explanation
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* SeatManager seatManager = new SeatManager(5); // Initializes a SeatManager with 5 seats.
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* seatManager.reserve(); // All seats are available, so return the lowest numbered seat, which is
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* 1.
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* seatManager.reserve(); // The available seats are [2,3,4,5], so return the lowest of them, which
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* is 2.
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* seatManager.unreserve(2); // Unreserve seat 2, so now the available seats are [2,3,4,5].
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* seatManager.reserve(); // The available seats are [2,3,4,5], so return the lowest of them, which
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* is 2.
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* seatManager.reserve(); // The available seats are [3,4,5], so return the lowest of them, which
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* is 3.
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* seatManager.reserve(); // The available seats are [4,5], so return the lowest of them, which is
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* 4.
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* seatManager.reserve(); // The only available seat is seat 5, so return 5.
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* seatManager.unreserve(5); // Unreserve seat 5, so now the available seats are [5].
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*
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* Constraints:
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*
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* 1 <= n <= 10^5
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* 1 <= seatNumber <= n
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* For each call to reserve, it is guaranteed that there will be at least one unreserved seat.
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* For each call to unreserve, it is guaranteed that seatNumber will be reserved.
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* At most 10^5 calls in total will be made to reserve and unreserve.
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******************************************************************************************************/
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class SeatManager {
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private:
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set<int> idle;
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public:
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SeatManager(int n) {
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for(int i=1; i<=n; i++) {
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idle.insert(i);
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}
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}
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int reserve() {
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auto it = idle.begin();
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auto seat = *it;
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idle.erase(it);
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return seat;
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}
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void unreserve(int seatNumber) {
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idle.insert(seatNumber);
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}
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};
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/**
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* Your SeatManager object will be instantiated and called as such:
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* SeatManager* obj = new SeatManager(n);
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* int param_1 = obj->reserve();
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* obj->unreserve(seatNumber);
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*/
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