City Sort

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

struct City
{
    double distance;
    std::vector<int> coordinates;
    bool operator<(const City& city) const {
        return this->distance < city.distance;
    }
    City(double d) : distance(d) {}
    City(const City &city) {
        this->distance = city.distance;
        this->coordinates = city.coordinates;
    }

    City& operator= (const City &city) {
        this->distance = city.distance;
        this->coordinates = city.coordinates;
        return *this;
    }
    // same for the greater-than operator but changing "<" to ">"
};

struct CitySortHelper {
    bool operator() (const City &x, const City &y) const { return x < y; }
} city_sort;

int main() {
    vector<City> cc;
    City a(1);
    City b(2);
    City c(11);
    City d(5);
    cc.push_back(a);
    cc.push_back(b);
    cc.push_back(c);
    cc.push_back(d);
    std::sort(cc.begin(), cc.end(), city_sort);
    for (int i = 0; i < cc.size(); i++) {
        cout << cc[i].distance << endl;
    }
    return 0;
}