OOP Design

Swap a Strategy at Runtime

Difficulty

Asked at Da Vinci Derivatives

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Available in Python and C++. You are solving it in C++. Switch to Python

xxxxxxxxx xxxxx xxxxxxxx xxxxxx xxx xx xxxxxx xxxx xxxxx xxx xxx xxx xxxx xx xx xxxxxxx, xxxxx xxx xxxxxxxx xxxxxxx. x xxxx xxxxxxx xxx xxxx xxxxxxxx xxxxxx xxxxxxxx xxxx xxxxxxxxxxxx xx xxxx xxxxxxx x xxxxxxx. x xxxxxxxx xxxxxxxxx xx x xxxxxx xxxxx xx xxxxxx, xxx xx xxxxxx xxxxxx xxxxx xxx xxxxxxx xxxx. xxx xxxxxxxx xxxxxxx xxx. xxxxxxxxx(xxxx): xxxxxx xxxx, xxxxxxxx xxx xxxxxx. xxxxxxxxxxxxxxxxx(xxxxx): xxxxxx * xxxxx / xxx, xxxxxxxxx xxxxxx xxxx. xxxxxxxx xxxxxx xxxxxxxx xxxxxxxx xx xxx xxxx x xxxxxxxx xxxx xxxxx: ( -xxx xxxxx x / xxx ) xx ( -x ), xxx ( -x ). xxxxxxxxxxx(xxxxx, xxxxx): xxxxxxxxxxxx, xxxxx xxxx xxxx xxxxx xx xxxxxx xxxxxxxxx. xxxxxx(xxxxx) xxxx xxx_xxxxx, xxxxx(xxxxxx), xxxxxxx() xxx x xxxxxxx xxxxxxxx(). xxxxx xxxxx xxxxxxx xxx xxxxxx, xxxx(xxxxxx), xxxxxxxxx xx xxxxxxx xxxx: xxxx xxxxxx xx xxx xxxxxx xxxxxxxxx xxx xxxxxx xxxx. xxxxxx xxxxx { xxxxxxx ~xxxxx() = xxxxxxx; xxxxxxx xxxx xxxx xxxx(xxxx xxxx xxxxxx) xxxxx = x; }; xxxxx xxxxxxxxx : xxxxxx xxxxx { xxxxxx: xxxxxxxx xxxxxxxxx(xxxx xxxx xxxx); /* ... */ }; xxxxx xxxxxxxxxxxxxxxxx : xxxxxx xxxxx { xxxxxx: xxxxxxxx xxxxxxxxxxxxxxxxx(xxxx xxxx xxxxx); /* ... */ }; xxxxx xxxxxxxxxxx : xxxxxx xxxxx { xxxxxx: xxxxxxxxxxx(xxxx xxxx xxxxx, xxxx xxxx xxxxx); /* ... */ }; xxxxx xxxxxx { xxxxxx: xxxxxxxx xxxxxx(xxx::xxxxxx_xxx<xxxxx> xxxxx); xxxx xxx_xxxxx(xxx::xxxxxx_xxx<xxxxx> xxxxx); xxxx xxxx xxxxx(xxxx xxxx xxxxxx); xxx::xxxxxx<xxx::xxxx<xxxx xxxx, xxxx xxxx>> xxxxxxx() xxxxx; xxxx xxxx xxxxxxxx() xxxxx; }; xxxxx xx xx xxxxxxxx xxxx xxxxx xxxx xxx xxxxxxx xxxxxx, xxxxx xxxxx xxxxxxx xxxx xx, xxx xxx xxxxxx xxxxx x xxx::xxxxxx_xxx<xxxxx>. xxx xxxxxx xxxx xxxx xxxxxx x xxxxx xxx xxxxxx xxx xxxxx xxxx xxxxxxx xxx xxx xxxxxxxx xx xxxxx. xxx xxxxxxx xx x xxxxxx xx {xxxxxx, xxxx} xxxxx. x++ xxxxxxx xxxxxxxx xxxxxxx xxxxxxxxx xxxxxx xxxx, xx x xxxxx xxxxxx * xxxxx / xxx xxxxx xxx xxxxx xxxx, xxx xxx xxxx xxx xx xxxxx xxxx. x xxxx xxxxx xxxxxx xxxx xxx xxxx xxxxx. xxxxxx xxxxxxx xxxxxx xxxx xxxxxx xxxxx xxx xxx xxxxxx xxx xxxx xxxx xxx. xxxxxxxx xxxxxx x(xxx::xxxx_xxxxxx<xxxxxxxxx>(x)); x.xxxxx(xxx); // x x.xxx_xxxxx(xxx::xxxx_xxxxxx<xxxxxxxxxxxxxxxxx>(x)); x.xxxxx(xxx); // x x.xxxxx(-xxx); // -x x.xxxxxxxx(); // x xxxxxxxxxxx xxx xxxxxx xxxx xxxxx xxx xxxx xxxx xx xxxxx xx xx xxxxxxx. xx xxxxxxx_xxxx, xx xxxx xxxx, xx xx/xxxx xxxx xxxxxxxx xxxxx. x xxx xxxxxxxx xxxxxx xxxx xx xxxxxx xx xxx xxxxxx xx xxx, xxx xxx xxxxxx xxxx xxxxxx xx x xxxxx xxxxx xx xxx xxxxx xxxx. xxxxx xxxxxxx xxx xxxx, xxxx xx xx xxx xxxxxxxx, xxx xxxxxxx xxx xxxxxx xxx xxx xxxx xx xxx xxxxxxx. xxx xxxxx xxx xxxxx xxxxxxxx.

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Language:

Python 3.12 C++23

Engine

#include <memory>
#include <utility>
#include <vector>

// ...
// ...
struct Sizer {
    virtual ~Sizer() = default;
    virtual long long size(long long signal) const = 0;
};

// ...
// ...
// ...
class FlatSizer : public Sizer {
public:
    explicit FlatSizer(long long lots) : lots_(lots) {}

    long long size(long long signal) const override {
        // ...
        (void)signal;
        return -999;
    }

private:
    long long lots_;
};

// ...
// ...
// ...
class ProportionalSizer : public Sizer {
public:
    explicit ProportionalSizer(long long scale) : scale_(scale) {}

    long long size(long long signal) const override {
        // ...
        (void)signal;
        return -999;
    }

private:
    long long scale_;
};

// ...
class CappedSizer : public Sizer {
public:
    CappedSizer(long long scale, long long limit) {
        // ...
        (void)scale;
        (void)limit;
    }

    long long size(long long signal) const override {
        // ...
        (void)signal;
        return -999;
    }

private:
    // ...
};

// ...
// ...
// ...
// ...
// ...
// ...
// ...
// ...
// ...
// ...
// ...
class Engine {
public:
    explicit Engine(std::shared_ptr<Sizer> sizer) {
        // ...
        (void)sizer;
    }

    void set_sizer(std::shared_ptr<Sizer> sizer) {
        // ...
        (void)sizer;
    }

    long long place(long long signal) {
        // ...
        (void)signal;
        return -999;
    }

    std::vector<std::pair<long long, long long>> history() const {
        // ...
        return {{-999, -999}};
    }

    long long position() const {
        // ...
        return -999;
    }

private:
    // ...
};

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