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// Copyright (c) 2009-2014 INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
// 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.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
// Author(s) : Samuel Hornus
#ifndef CGAL_INTERNAL_COMBINATION_ENUMERATOR_H
#define CGAL_INTERNAL_COMBINATION_ENUMERATOR_H
#include <CGAL/basic.h>
#include <vector>
namespace CGAL {
namespace internal {
class Combination_enumerator
{
// types and member data
typedef std::vector<int> Combination;
Combination combi_;
const int k_;
const int min_;
const int max_;
const int max_at_pos_0_;
public:
// For generating all the combinations of |k| distinct elements in the
// interval [min, max] (both included)
Combination_enumerator(const int k, const int min, const int max)
: combi_(k), k_(k), min_(min), max_(max), max_at_pos_0_(max + 1 - k)
{
CGAL_assertion_msg( min <= max, "min is larger than max");
CGAL_assertion_msg( 1 <= k && k <= ( max - min + 1 ), "wrong value of k");
init();
}
Combination_enumerator(const Combination_enumerator & c)
: combi_(c.combi_), k_(c.k_), min_(c.min_), max_(c.max_), max_at_pos_0_(c.max_at_pos_0_)
{}
int number_of_elements()
{
return k_;
}
void init()
{
combi_.resize(k_);
for( int i = 0; i < k_; ++i )
element(i) = min_ + i;
}
bool end() const
{
return ( element(0) > max_at_pos_0_ );
}
int element(const int i) const
{
CGAL_assertion( 0 <= i && i < k_ );
return combi_[i];
}
int & element(const int i)
{
CGAL_assertion( 0 <= i && i < k_ );
return combi_[i];
}
int operator[](const int i) const
{
return element(i);
}
int & operator[](const int i)
{
return element(i);
}
void operator++()
{
int i = k_ - 1;
int max_at_pos_i(max_);
while( ( i >= 0 ) && ( element(i) >= max_at_pos_i ) )
{
--i;
--max_at_pos_i;
}
if( -1 == i )
{
if( element(0) == max_at_pos_0_ )
++element(0); // mark then end of the enumeration with an impossible value
// Note than when we have arrived at the end of the enumeration, applying
// operator++() again does not change anything, so it is safe to
// apply it too many times.
}
else
{
++element(i);
for( int j = i + 1; j < k_; ++j )
element(j) = element(i) + j - i;
}
}
Combination_enumerator operator++(int)
{
Combination_enumerator tmp(*this);
++(*this);
return tmp;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - TESTING
#if 0
void test()
{
std::cerr << '\n';
while( ! end() )
{
std::cerr << '\n';
for( int i = 0; i < k_; ++i )
std::cerr << element(i) << ' ';
++(*this);
}
init();
}
#endif
};
} // end of namespace internal
} // end of namespace CGAL
#endif // CGAL_INTERNAL_COMBINATION_ENUMERATOR_H
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