BubbleSort

#include <iostream>
#include <vector>
using std::cin;
using std::cout;
using std::vector;

struct CPoint {
    int X;
    int Y;
    CPoint( int x, int y ) : X( x ), Y( y ) {}
};

// Вариант 1.
// Оператор сравнения по удаленности точки от (0, 0).
bool operator<( const CPoint& first, const CPoint& second )
{
    return first.X * first.X + first.Y * first.Y <
        second.X * second.X + second.Y * second.Y;
}

bool operator<=( const CPoint& first, const CPoint& second )
{
    return !( second < first );
}

bool operator>( const CPoint& first, const CPoint& second )
{
    return second < first;
}

bool operator>=( const CPoint& first, const CPoint& second )
{
    return !( first < second );
}

// Вариант 2. Функция сравнения.
bool CompareByDistanceFromZero( const CPoint& first, const CPoint& second )
{
    return first.X * first.X + first.Y * first.Y <
        second.X * second.X + second.Y * second.Y;
}

// Сортировка пузырьком.
template<class T>
void BubbleSort( vector<T>& arr, bool (* compareFunction)( const T&, const T& ) )
{
    int n = arr.size();
    for( int i = n - 2; i >= 0; --i ) { // n - 1 итерация.
        for( int j = 0; j <= i; ++j ) {
            if( compareFunction( arr[j + 1], arr[j] ) ) {
                std::swap( arr[j], arr[j + 1] );
            }
        }
    }
}

int main()
{
    vector<CPoint> arr;
    int x = 0;
    int y = 0;
    while( cin >> x >> y ) {
        arr.push_back( CPoint( x, y ) );
    }

    BubbleSort( arr, CompareByDistanceFromZero );

    for( int i = 0; i < static_cast<int>( arr.size() ); ++i ) {
        cout << arr[i].X << ' ' << arr[i].Y << std::endl;
    }
    return 0;
}