112 lines
3.1 KiB
C++
112 lines
3.1 KiB
C++
// Solutions to the Advent Of Code 2024.
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// Copyright (C) 2025 Stefan Müller
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//
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// This program is free software: you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free Software
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// Foundation, either version 3 of the License, or (at your option) any later
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// version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along with
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// this program. If not, see <http://www.gnu.org/licenses/>.
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#pragma once
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#include <iterator>
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#include <vector>
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class GraphBase
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{
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public:
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size_t getNVertices() const;
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size_t getNEdges() const;
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bool areAdjacent(const int vertex1, const int vertex2) const;
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struct Incidence
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{
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public:
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Incidence(const int vertex, const int edge)
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: vertex{ vertex }, edge{ edge }
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{
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}
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int vertex;
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int edge;
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};
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struct NeighborIterator
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{
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public:
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// Iterator traits.
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using difference_type = std::ptrdiff_t;
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using value_type = Incidence;
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using pointer = const value_type*;
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using reference = const value_type&;
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using iterator_category = std::forward_iterator_tag;
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NeighborIterator(const GraphBase& graph, const int vertex)
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: graph_{ graph }, incidence_{ -1 }, value_{ -1, -1 }
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{
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if (vertex >= 0 && vertex < graph_.firstVertexIncidences.size())
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{
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setIncidence(graph_.firstVertexIncidences[vertex]);
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}
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};
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NeighborIterator& operator++()
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{
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if (incidence_ >= 0)
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{
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setIncidence(graph_.nextIncidences[incidence_]);
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}
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return *this;
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}
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NeighborIterator operator++(int)
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{
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NeighborIterator it = *this;
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++(*this);
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return it;
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}
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bool operator==(NeighborIterator other) const
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{
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return incidence_ == other.incidence_;
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}
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bool operator!=(NeighborIterator other) const
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{
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return !(*this == other);
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}
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const reference operator*() const
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{
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return value_;
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}
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const pointer operator->() const
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{
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return &value_;
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}
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private:
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const GraphBase& graph_;
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int incidence_;
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value_type value_;
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void setIncidence(const int incidence)
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{
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incidence_ = incidence;
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if (incidence_ >= 0)
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{
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value_ = { graph_.incidenceVertices[incidence_], incidence_ >> 1 };
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}
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}
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};
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NeighborIterator begin(const int vertex) const;
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NeighborIterator end() const;
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protected:
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std::vector<int> firstVertexIncidences{};
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std::vector<int> nextIncidences{};
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std::vector<int> incidenceVertices{};
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int addVertexInternal();
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void addEdgeInternal(const int vertex1, const int vertex2);
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};
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