c++ 질문입니다. 도와주세요.

#include <iostream>
#include <unordered_map>
 
class CachingCalculator
{
	class Arguments
	{
	public:
		Arguments(int firstArgument, int secondArgument)
		{
			this->firstArgument = firstArgument;
			this->secondArgument = secondArgument;
		}
 
		int firstArgument;
		int secondArgument;
	};
 
        class Hasher {
            public:
                std::size_t operator()(Arguments* const &k) const {
                    return std::hash<int>()(k->firstArgument) ^ std::hash<int>()(k->secondArgument);
                }
        };
 
        class Comparator {
            public:
                bool operator()(Arguments* const& t1, Arguments* const& t2) const {
                    return ((t1->firstArgument == t2->firstArgument) && (t1->secondArgument == t2->secondArgument));
                }
        };
 
        typedef std::unordered_map<Arguments*, int, Hasher, Comparator> ArgumentMap;
 
public:
	CachingCalculator(int(*func)(int, int))
	{
		this->func = func;
	}
 
	~CachingCalculator()
	{
		for (ArgumentMap::iterator it = calculations.begin(); it != calculations.end(); ++it)
		{
			delete it->first;
		}
	}
 
	int calculate(int firstArgument, int secondArgument)
	{
		Arguments* args = new Arguments(firstArgument, secondArgument);
 
		ArgumentMap::iterator it = calculations.find(args);
		if (it != calculations.end())
			return it->second;
 
		int calculation = func(firstArgument, secondArgument);
		calculations[args] = calculation;
		return calculation;
	}
 
private:
	ArgumentMap calculations;
	int(*func)(int, int);
};
 
int modulo(int a, int b)
{
	std::cout << "Function modulo has been called.\n";
	return a % b;
}
 
int main(int argc, const char* argv[])
{
	CachingCalculator calculator(modulo);
 
	// Function modulo should be called.
	std::cout << calculator.calculate(5, 2) << '\n';
 
	// Function modulo should be called.
	std::cout << calculator.calculate(7, 4) << '\n';
 
	// Function modulo shouldn't be called because we have already made a call with arguments (5, 2)!
	// Instead, result should be pulled from the cache!
	std::cout << calculator.calculate(5, 2) << '\n';
 
	return 0;
}