FixPoint (ラムダ式の再帰)
(Util/fix-point.hpp)

#pragma once
#include <functional>

/**
 * @brief FixPoint (ラムダ式の再帰)
 *
 * (Ex) FixPoint([&](auto func, int n) -> int {...})(10);
 */
template <class F>
struct FixPoint : F {
    FixPoint(F&& f)
        : F(std::forward<F>(f)) {}

    template <class... Args>
    decltype(auto) operator()(Args&&... args) const {
        return F::operator()(*this, std::forward<Args>(args)...);
    }
};

#line 2 "Util/fix-point.hpp"
#include <functional>

/**
 * @brief FixPoint (ラムダ式の再帰)
 *
 * (Ex) FixPoint([&](auto func, int n) -> int {...})(10);
 */
template <class F>
struct FixPoint : F {
    FixPoint(F&& f)
        : F(std::forward<F>(f)) {}

    template <class... Args>
    decltype(auto) operator()(Args&&... args) const {
        return F::operator()(*this, std::forward<Args>(args)...);
    }
};