2 策略模式（1）

#include <iostream>
#include <string>

 using std::cout;
 using std::endl;

 class Strategy
{
public:
    virtual void AlgorithmInterface() = 0;
};

//具体算法A
class ConcreteStrategyA : public Strategy
{
public:
    void AlgorithmInterface()
    {
        cout<<"算法A实现"<<endl;
    }
};

//具体算法B
class ConcreteStrategyB : public Strategy
{
public:
    void AlgorithmInterface()
    {
        cout<<"算法B实现"<<endl;
    }
};

//具体算法A
class ConcreteStrategyC : public Strategy
{
public:
    void AlgorithmInterface()
    {
        cout<<"算法C实现"<<endl;
    }
};

//Context,用一个ConcreteStrategy来配置，维护一个对Strategy对象的引用
class Context
{
public:
    Context(Strategy* strategy) //初始化时，传入具体的策略对象
    {
        this->strategy = strategy;
    }
    void ContextInterface() //根据具体的策略对象，调用其算法的方法
    {
        strategy->AlgorithmInterface();
    }
private:
    Strategy* strategy;
};

int main()
{
    //客户端代码
    Context* context = NULL;
    
    context = new Context(new ConcreteStrategyA());
    context->ContextInterface();

    context = new Context(new ConcreteStrategyB());
    context->ContextInterface();

    context = new Context(new ConcreteStrategyC());
    context->ContextInterface();

    return 0;
}