48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
#pragma once
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#include <cassert>
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#include <set>
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#include <boost/container/flat_set.hpp>
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// Using boost flat set was faster than std::set.
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namespace detail {
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template <typename Field>
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auto same_group(Field const & field, typename Field::Position const & p, typename Field::Position const & q){
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return field.get(p) == field.get(q);
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}
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template <typename Field>
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void cluster_expand(Field const & field, typename Field::Position const & p, boost::container::flat_set<typename Field::Position>& ret){
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for(auto&& q : field.neighbors(p)){
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if(!same_group(field, p, q)) continue;
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if(ret.insert(q).second){
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cluster_expand(field, q, ret);
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}
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}
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}
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}
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template <typename Field>
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auto cluster_at(Field const & field, typename Field::Position const & p){
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boost::container::flat_set<typename Field::Position> ret;
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ret.reserve(10); // speed improvement of 20%
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ret.insert(p);
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detail::cluster_expand(field, p, ret);
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return ret;
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}
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template <typename Field>
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auto all_clusters(Field const & field){
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boost::container::flat_set<decltype(cluster_at(field, std::declval<typename Field::Position>()))> ret;
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ret.reserve(10);
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for(auto&& p : field.all_positions()){
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if(field.empty(p)) continue;
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ret.insert(cluster_at(field, p));
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}
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return ret;
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}
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#undef Set
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