Bloom Your
C++ Skills

				
					#include <algorithm>
#include <cmath>
#include <iostream>
#include <unordered_map>

struct Point {
    int x;
    int y;

    bool operator==(const Point & other) const {
        return x == other.x && y == other.y;
    }
};

double radius(Point p) {
    return std::sqrt(p.x * p.x + p.y * p.y);
}

namespace std {
    template<>
    struct hash<Point> {
        std::size_t operator()(const Point & p) const noexcept
        {
            std::size_t h1 = std::hash<int>{}(p.x);
            std::size_t h2 = std::hash<int>{}(p.y);
            return h1 & (h2 << 1); // or use boost::hash_combine
        }
    };
}

int main() {
    std::unordered_map<Point, std::string> citiesInverted {
        {{151, -33}, "Sydney"},
        {{17, 51}, "Wrocław"},
        {{37, 55}, "Moskwa"},
        {{-74, 40}, "Nowy Jork"}
    };

    auto isCloserThan70 = [](auto coord){ return radius(coord) < 70; };

    for (auto & [coord, city] : citiesInverted) {
        if (isCloserThan70(coord)) {
            std::cout << city << " " << radius(coord) << '\n';
        }
    }

    return 0;
}