97 lines
2.5 KiB
C++
97 lines
2.5 KiB
C++
#ifndef HENZINGER_KING_H_
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#define HENZINGER_KING_H_
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#include "algorithm/dynamic_reachability.h"
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#include "algorithm/frigioni.h"
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using namespace graph;
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constexpr int threshold = 5;
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namespace algo {
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template<typename T>
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class HenzingerKing : public DynamicReachability<T> {
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public:
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HenzingerKing() = default;
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HenzingerKing(Digraph<T> G) { this->G = G; }
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// Initialize decremental maintenance data structure and the empty set S
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void init() override;
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// Execute query q(u, v) from vertex u to vertex v by querying the
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// decremental reachability data structure at the start of the phase
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// and then if necessary check the set S
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bool query(const T& u, const T& v) override;
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// Remove collection of edges from the decremental maintenance data structure
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// and for every vertex in set S, rebuilt reachability trees from scratch
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void remove(const std::vector<std::pair<T,T>>& edges);
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// Insert collection of edges in set S, if threshold is reached re-initialize
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// algorithm, otherwise construct reachability trees for the vertex that is
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// the center-of-insertions
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void insert(const T& c, const std::vector<T>& vertices);
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private:
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// Decremental maintenance data structure
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Frigioni<T> frigioni;
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// Collection of vertices that have been centers of insertions in this phase
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std::set<T> S;
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// Maintain in-out bfs trees
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std::unordered_map<T, BreadthFirstTree<T>> In;
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std::unordered_map<T, BreadthFirstTree<T>> Out;
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};
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template<typename T>
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void HenzingerKing<T>::init() {
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S.clear();
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frigioni = Frigioni<T>(this->G);
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frigioni.init();
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}
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template<typename T>
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bool HenzingerKing<T>::query(const T& u, const T& v) {
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if (frigioni.query(u, v))
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return true;
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return std::any_of(S.begin(), S.end(),
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[&](const T& w) {
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return In[w].adjList.contains(u) &&
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Out[w].adjList.contains(v);
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});
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}
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template<typename T>
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void HenzingerKing<T>::remove(const std::vector<std::pair<T, T>>& edges) {
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for (const auto& [u, v] : edges) {
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this->G.remove(u, v);
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}
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frigioni.remove(edges);
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for (const auto& w : S) {
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In[w] = BreadthFirstTree(this->G.reverse(), w);
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Out[w] = BreadthFirstTree(this->G, w);
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}
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}
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template<typename T>
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void HenzingerKing<T>::insert(const T& c, const std::vector<T>& vertices) {
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for (const auto& w : vertices)
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this->G.insert(c, w);
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S.insert(c);
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if (S.size() > threshold) {
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init();
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return;
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}
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In[c] = BreadthFirstTree(this->G.reverse(), c);
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Out[c] = BreadthFirstTree(this->G, c);
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}
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} // namespace algo
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#endif |