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// Copyright 2008, 2009 Brady J. Garvin
// This file is part of Covering Arrays by Simulated Annealing (CASA).
// CASA 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.
// CASA 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 CASA. If not, see <http://www.gnu.org/licenses/>.
#ifndef GREEDYFILTER_H
#define GREEDYFILTER_H
#include "search/Filter.H"
// A specialization of Filter where only the heuristically best child is
// explored. Furthermore, if given the option to treat the parent as a child,
// the filter will only have the search explore children if at least one of them
// is heuristically better than the parent.
template<class STATE, class COST>class GreedyFilter :
public Filter<STATE, COST> {
typedef Heuristic<STATE, COST> HeuristicT;
typedef Goal<STATE> GoalT;
public:
void operator()
(std::set<STATE>&children, const HeuristicT&heuristic, const GoalT&goal)
const {
typename std::set<STATE>::iterator best = children.end();
COST score = 0;
for(typename std::set<STATE>::iterator
iterator = children.begin(),
end = children.end();
iterator != end;
++iterator) {
COST estimate = heuristic.estimate(*iterator, goal);
if (best == children.end() || estimate < score) {
best = iterator;
score = estimate;
}
}
for(typename std::set<STATE>::iterator
iterator = children.begin(),
end = children.end();
iterator != end;){
if (iterator == best) {
++iterator;
} else {
children.erase(iterator++);
}
}
}
};
#endif
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