OJ lintcode 玩具工厂

工厂模式是一种常见的设计模式。请实现一个玩具工厂 ToyFactory 用来产生不同的玩具类。可以假设只有猫和狗两种玩具。
您在真实的面试中是否遇到过这个题？
Yes
样例
ToyFactory tf = ToyFactory();
Toy toy = tf.getToy('Dog');
toy.talk();

Wow

toy = tf.getToy('Cat');
toy.talk();

Meow

/**
 * Your object will be instantiated and called as such:
 * ToyFactory* tf = new ToyFactory();
 * Toy* toy = tf->getToy(type);
 * toy->talk();
 */
class Toy {
public:
    virtual void talk() const = 0;
};

class Dog : public Toy {
    // Write your code here
public:
     void talk() const {
        cout << "Wow" << endl;
    }
};

// 基类中又const ，那么继承的派生类中必须要又const ，否则编译不通过
class Cat : public Toy {
    // Write your code here
public:
    void talk() const {
        cout << "Meow" << endl;
    }
};


// 基类中又const ，那么继承的派生类中必须要又const ，否则编译不通过
class ToyFactory {
public:
    /**
    * @param type a string
    * @return Get object of the type
    */
    Toy* getToy(string& type) {
        // Write your code here
        Toy * t;
        if (type == "Dog") {
            t = new Dog();
            return t;
        }
        if (type == "Cat") {
            t = new Cat();
            return t;
        }
        return NULL;
    }
};