#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

bool cmp_abs(int i, int j);
void printArray(
    std::vector<int>::const_iterator first,
    std::vector<int>::const_iterator last
);

class CmpMod {
    int m;
public:
    CmpMod(int mm = 5):
        m(mm)
    {}

    bool operator()(int i0, int i1) const {
        int r0 = i0 % m;
        if (r0 < 0)
            r0 += m;
        int r1 = i1 % m;
        if (r1 < 0)
            r1 += m;
        return (r0 < r1);
    }
};

int main() {
    std::vector<int> a = {
        1, -10, 22, 36, -57, 102, 17, 19, 28, 15,
        12, 18, -121, 343, -561
    };
    std::cout << "Initial array:" << std::endl;
    printArray(a.cbegin(), a.cend());
    std::cout << "----" << std::endl;

    std::vector<int> b = a;
    std::sort(b.begin(), b.end());
    std::cout << "Sorted by value:" << std::endl;
    printArray(b.cbegin(), b.cend());
    std::cout << "----" << std::endl;

    b = a;
    std::sort(b.begin(), b.end(), cmp_abs);
    std::cout << "Sorted by absolute value:" << std::endl;
    printArray(b.cbegin(), b.cend());
    std::cout << "----" << std::endl;

    b = a;
    int m = 10;
    std::sort(b.begin(), b.end(), CmpMod(10));
    std::cout << "Sorted by residues modulo " << m << ":" << std::endl;
    printArray(b.cbegin(), b.cend());
    std::cout << "----" << std::endl;

    return 0;
}

bool cmp_abs(int i0, int i1) {
    return (abs(i0) < abs(i1));
}

void printArray(
    std::vector<int>::const_iterator first,
    std::vector<int>::const_iterator last
) {
    int i = 0;
    while (first != last) {
        if (i > 0) {
            // Print a delimiter
            if (i%5 == 0)
                std::cout << std::endl;
            else
                std::cout << " ";
        }
        std::cout << *first;
        ++first; ++i;
    }
    std::cout << std::endl;
}