《Cracking the Coding Interview》——第8章：面向对象设计——题目2

2014-04-23 17:45

题目：假设有个呼叫中心，有接线员、经理、主管三种角色。如果接线员无法处理呼叫，就上传给经理；如果仍无法处理，则上传给主管。请用代码描述这一过程。

解法：第一眼觉得这题肯定是在考察设计模式，很像exception的throw过程。对于我这种对设计模式一窍不通的人，这题还无法很好解答。待稍后专门学习设计模式之后，再回来好好琢磨一遍。

代码：

// 8.2 Design a call center system to handle calls, the order will be respondent->manager->director, find the first employee to handle a call.
#include <iostream>
#include <vector>
using namespace std;

class People {
public:
    People() {};
    virtual void handle() = 0;
    virtual ~People() {};
};

class Respondent: public People {
public:
    Respondent() {};
    void handle() {
        cout << "Respondent is handling the call." << endl;
    };
    ~Respondent() {};
};

class Manager: public People {
public:
    Manager() {};
    void handle() {
        cout << "Manager is handling the call." << endl;
    };
    ~Manager() {};
};

class Director: public People {
public:
    Director() {};
    void handle() {
        cout << "Director is handling the call." << endl;
    };
    ~Director() {};
};

class CallCenter {
public:
    CallCenter(int num_respondent = 0, int num_manager = 0, int num_director = 0) {
        respondents.resize(num_respondent);
        managers.resize(num_manager);
        directors.resize(num_director);
        respondents_available.resize(num_respondent);
        managers_available.resize(num_manager);
        directors_available.resize(num_director);
        fill(respondents_available.begin(), respondents_available.end(), true);
        fill(managers_available.begin(), managers_available.end(), true);
        fill(directors_available.begin(), directors_available.end(), true);
    }
    
    void handle() {
        size_t i;
        
        for (i = 0; i < respondents.size(); ++i) {
            if (respondents_available[i]) {
                break;
            }
        }
        if (i < respondents.size()) {
            respondents_available[i] = false;
            respondents[i].handle();
            respondents_available[i] = true;
            return;
        }

        for (i = 0; i < managers.size(); ++i) {
            if (managers_available[i]) {
                break;
            }
        }
        if (i < managers.size()) {
            managers_available[i] = false;
            managers[i].handle();
            managers_available[i] = true;
            return;
        }
        
        for (i = 0; i < directors.size(); ++i) {
            if (directors_available[i]) {
                break;
            }
        }
        if (i < directors.size()) {
            directors_available[i] = false;
            directors[i].handle();
            directors_available[i] = true;
            return;
        }
    }
private:
    vector<Respondent> respondents;
    vector<Manager> managers;
    vector<Director> directors;
    vector<bool> respondents_available;
    vector<bool> managers_available;
    vector<bool> directors_available;
};

int main()
{
    CallCenter *p_call_center = nullptr;
    int r, m, d;
    
    while (cin >> r >> m >> d) {
        p_call_center = new CallCenter(r, m, d);
        p_call_center->handle();
        delete p_call_center;
        p_call_center = nullptr;
    }
    
    return 0;
}