《Cracking the Coding Interview》——第8章：面向对象设计——题目4

2014-04-23 18:17

题目：设计一个停车位的类。

解法：停车位，就要有停车、取车的功能了。另外我还加了一个工作线程用于计费，每秒给那些有车的车位加1块钱费用。

代码：

 // 8.4 Design a class to simulate the parking lot.
 #include <iostream>
 #include <string>
 #include <thread>
 #include <vector>
 using namespace std;

 class ParkingLot {
 public:
     ParkingLot(int _capacity = ):capacity(_capacity) {
         slots.resize(capacity);
         fees.resize(capacity);
         fill(slots.begin(), slots.end(), false);
         fill(fees.begin(), fees.end(), );
     };

     void start() {
         work = new thread(workThread, this);
     };

     void parkIn() {
         int i;

         for (i = ; i < (int)slots.size(); ++i) {
             if (!slots[i]) {
                 cout << "Car is parked at slot " << i << "." << endl;
                 slots[i] = true;
                 fees[i] = ;
                 return;
             }
         }

         cout << "Sorry, no more slot is available." << endl;
     };

     void getOut(int id) {
         if (id <  || id > (int)slots.size() - ) {
             cout << "Invalid slot number." << endl;
             return;
         } else if (slots[id] == false) {
             cout << "The slot is empty." << endl;
             return;
         }

         cout << "Car in slot " << id << " is delivered. Total fee is " << fees[id] << " bucks." << endl;
         slots[id] = false;
         fees[id] = ;
     };

     friend void workThread(ParkingLot *);

     ~ParkingLot() {
         slots.clear();
         fees.clear();
         work->detach();
         delete work;
     };
 private:
     thread *work;
     int capacity;
     vector<bool> slots;
     vector<int> fees;
 };

 void workThread(ParkingLot *p)
 {
     while (true) {
         // sleep for one second.
         _sleep();
         for (int i = ; i < p->capacity; ++i) {
             if (p->slots[i]) {
                 ++p->fees[i];
             }
         }
     }
 }

 int main()
 {
     ParkingLot *p;
     string cmd;
     int id;

     p = new ParkingLot();
     p->start();
     while (cin >> cmd) {
         if (cmd == "park") {
             p->parkIn();
         } else if (cmd == "get") {
             cin >> id;
             p->getOut(id);
         } else if (cmd == "end") {
             break;
         }
     }
     delete p;

     return ;
 }