pointgenerator.cpp

#include <algorithm>
#include <unordered_set>
#include <random>
#include <iostream>

struct Point final {
	const int x;
	const int y;
	
	Point() : x(0), y(0) {}
	Point(int x, int y) : x(x), y(y) {}
	~Point() = default;
	
	bool operator ==(const Point& other) const {
		return x == other.x && y == other.y;
	}
};

// Hack in a hash implementation for Point
namespace std {
	template<> struct hash<Point> {
		using argument_type = Point;
		using result_type = std::size_t;
		result_type operator ()(const argument_type& v) const noexcept {
			const result_type hx(std::hash<int>{}(v.x));
			const result_type hy(std::hash<int>{}(v.y));
			return hx ^ (hy << 8 * (sizeof(std::size_t) - sizeof(int)));
		}
	};
}

std::unordered_set<Point> positions {};

std::random_device randomDevice;
std::mt19937 mt {randomDevice()};
std::uniform_int_distribution<> coordDistribution {0, 15};

const Point& generateFoodPos() {
	for (;;) {
		// [iterator, inserted]
		const auto result = positions.emplace(coordDistribution(mt),
		                                      coordDistribution(mt));
		if (result.second) return *result.first;
	}
}

int main() {
	for (int i = 0; i < 5; ++i) {
		const auto& point = generateFoodPos();
		std::cout << point.x << "," << point.y << "\n";
	}
	std::cout << "\n" << positions.size() << "\n";
	return 0;
}

c++ -g -std=c++17 -Wall -Wextra -pedantic -o pointgenerator pointgenerator.cpp