6.1.7.1 Set-related operations

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>

using namespace std;

struct Country
{
    string name;
    int area;
    friend std::ostream& operator<< (std::ostream &out, const Country &c);
};
std::ostream& operator<< (std::ostream &out, const Country &c)
{
    out << c.name << " " << c.area;

    return out;
}

bool compare(Country lhs, Country rhs)
{
    return lhs.area < rhs.area;
}

int main()
{
    vector <Country> countries = {
            { "India", 3287 },{ "Argentina", 2780 },
            { "Brazil", 8515 },{ "Australia", 7692 },
            { "China", 9572 },{ "United States of America", 9525 },
            { "Russia", 17098 },{ "Canada", 9984 },
            { "Kazakhstan", 	2724 },{ "Algeria", 2381 }
    };
    vector <Country> countries_small = {
            { "Brazil", 8515 },{ "Australia", 7692 },
            { "Kazakhstan", 	2724 },{ "Algeria", 2381 }
    };

    sort(countries.begin(), countries.end(),compare);
    sort(countries_small.begin(), countries_small.end(),compare);

    cout << *(min_element(countries.begin(),countries.end(),compare)) << endl;
    cout << *(min_element(countries_small.begin(),countries_small.end(),compare)) << endl;
    cout << *(max_element(countries.begin(),countries.end(),compare)) << endl;
    cout << *(max_element(countries_small.begin(),countries_small.end(),compare)) << endl;

    return 0;
}