// This file is one of a series that demonstrates how to write & use
// a comparison functor for an STL container.
//
// This version uses a comparison functor that does a two-level comparison.
// This is similar to sorting names by last name, then by first name.

#include <iostream>
#include <set>
#include <algorithm>
#include <iterator>
#include <cstdlib>

using namespace std;

struct compare {
    // Primary sort: distance from 50
    // Secondary sort: value of number
    bool operator()(int a, int b) const {
    	int da = abs(a-50), db = abs(b-50);
	if (da != db)
		return da < db;
	return a < b;
    }
};

int main() {
    int values[] = {31, 41, 59, 26, 53, 58, 97, 93, 23, 84};
    set<int, compare> s(values, values+10);
    copy(s.begin(), s.end(), ostream_iterator<int>(cout, " "));
    cout << '\n';
}