InducedEquivalence.h

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/*
 * This file is part of Algorithms library toolkit.
 * Copyright (C) 2017 Jan Travnicek (jan.travnicek@fit.cvut.cz)
 
 * Algorithms library toolkit is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 
 * Algorithms library toolkit is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 
 * You should have received a copy of the GNU General Public License
 * along with Algorithms library toolkit.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include <alib/set>
#include <alib/map>
 
namespace relation {
 
class InducedEquivalence {
public:
    template < class T >
    static ext::set < ext::set < T > > inducedEquivalence ( const ext::set < ext::pair < T, T > > & relation );
};
 
template < class T >
ext::set < ext::set < T > > InducedEquivalence::inducedEquivalence ( const ext::set < ext::pair < T, T > > & relation ) {
    ext::map < T, ext::set < T > > transform;
 
    for ( const ext::pair < T, T > & item : relation ) {
        transform [ item.first ].insert ( item.second );
    }
 
    ext::set < ext::set < T > > res;
 
    for ( const std::pair < const T, ext::set < T > > & item : transform ) {
        res.insert ( item.second );
    }
 
    return res;
}
 
} /* namespace relation */