IsTransitive.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/pair>
 
namespace relation {
 
class IsTransitive {
public:
    template < class T >
    static bool isTransitive ( const ext::set < ext::pair < T, T > > & relation );
};
 
template < class T >
bool IsTransitive::isTransitive ( const ext::set < ext::pair < T, T > > & relation ) {
    for ( const ext::pair < T, T > & ab : relation )
        for ( const ext::pair < T, T > & bc : relation )
            if ( ab.second == bc.first && ! relation.contains ( ext::make_pair ( ab.first, bc.second ) ) )
                return false;
 
    return true;
}
 
} /* namespace relation */