From b38b4bf78294b1c61d6d3ab98b1b8445a514d1cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Uhl=C3=ADk?= <jan@uhlik.me>
Date: Thu, 29 Mar 2018 20:57:54 +0200
Subject: [PATCH] Add SPFA algorithm.
---
alib2graph_algo/src/shortest_path/SPFA.cpp | 66 +++++++
alib2graph_algo/src/shortest_path/SPFA.hpp | 212 +++++++++++++++++++++
2 files changed, 278 insertions(+)
create mode 100644 alib2graph_algo/src/shortest_path/SPFA.cpp
create mode 100644 alib2graph_algo/src/shortest_path/SPFA.hpp
diff --git a/alib2graph_algo/src/shortest_path/SPFA.cpp b/alib2graph_algo/src/shortest_path/SPFA.cpp
new file mode 100644
index 0000000000..a3ffb2943f
--- /dev/null
+++ b/alib2graph_algo/src/shortest_path/SPFA.cpp
@@ -0,0 +1,66 @@
+// SPFA.cpp
+//
+// Created on: 05. 03. 2018
+// Author: Jan Uhlik
+// Modified by:
+//
+// Copyright (c) 2017 Czech Technical University in Prague | Faculty of Information Technology. All rights reserved.
+// Git repository: https://gitlab.fit.cvut.cz/algorithms-library-toolkit/automata-library
+
+#include "SPFA.hpp"
+
+#include <registration/AlgoRegistration.hpp>
+
+namespace {
+
+auto SPFA1 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedUndirectedGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFA2 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedUndirectedMultiGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFA3 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedDirectedGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFA4 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedDirectedMultiGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFA5 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedMixedGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFA6 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+ const graph::WeightedMixedMultiGraph<> &,
+ const DefaultNodeType &,
+ const DefaultNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFAGrid1 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultSquareGridNodeType>,
+ DefaultWeightType>,
+ const grid::WeightedSquareGrid4<> &,
+ const DefaultSquareGridNodeType &,
+ const DefaultSquareGridNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+auto SPFAGrid2 = registration::AbstractRegister<shortest_path::SPFA,
+ ext::pair<ext::vector<DefaultSquareGridNodeType>,
+ DefaultWeightType>,
+ const grid::WeightedSquareGrid8<> &,
+ const DefaultSquareGridNodeType &,
+ const DefaultSquareGridNodeType &>(shortest_path::SPFA::findPathRegistration);
+
+}
diff --git a/alib2graph_algo/src/shortest_path/SPFA.hpp b/alib2graph_algo/src/shortest_path/SPFA.hpp
new file mode 100644
index 0000000000..158985496f
--- /dev/null
+++ b/alib2graph_algo/src/shortest_path/SPFA.hpp
@@ -0,0 +1,212 @@
+// SPFA.hpp
+//
+// Created on: 05. 03. 2018
+// Author: Jan Uhlik
+// Modified by:
+//
+// Copyright (c) 2017 Czech Technical University in Prague | Faculty of Information Technology. All rights reserved.
+// Git repository: https://gitlab.fit.cvut.cz/algorithms-library-toolkit/automata-library
+
+#ifndef ALIB2_SPFA_HPP
+#define ALIB2_SPFA_HPP
+
+#include <alib/list>
+#include <alib/set>
+#include <alib/map>
+#include <alib/vector>
+#include <queue>
+#include <stdexcept>
+#include <functional>
+#include <algorithm>
+
+#include <common/ReconstructPath.hpp>
+#include <common/SupportFunction.hpp>
+
+namespace shortest_path {
+
+class SPFA {
+// ---------------------------------------------------------------------------------------------------------------------
+ public:
+
+ /// Run SPFA algorithm from the \p start node in the \p graph.
+ ///
+ /// Whenever node is opened, \p f_user is called with two parameters (the opened node and value of currently shortest path).
+ ///
+ /// \param graph to explore.
+ /// \param start initial node.
+ /// \param f_user function which is called for every opened node with value of currently shortest path.
+ ///
+ /// \note TEdge of \p graph must follow graph::edge::WeightedEdge interface.
+ /// \sa graph::edge_type::WeightedEdge.
+ ///
+ /// \throws std::out_of_range if \p graph contains negative cycle.
+ ///
+ template<
+ typename TGraph,
+ typename TNode,
+ typename F = std::function<void(const TNode &,
+ const typename TGraph::edge_type::weight_type &)> >
+ static
+ void
+ run(const TGraph &graph,
+ const TNode &start,
+ F f_user = [](const TNode &,
+ const typename TGraph::edge_type::weight_type &) -> void {});
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+ /// Find the shortest path using SPFA algorithm from the \p start node to the \p goal node in the \p graph.
+ ///
+ /// Whenever node is opened, \p f_user is called with two parameters (the opened node and value of currently shortest path).
+ ///
+ /// \param graph to explore.
+ /// \param start initial node.
+ /// \param goal final node.
+ /// \param f_user function which is called for every open node with value of currently shortest path.
+ ///
+ /// \returns pair where first := shortest path := distance of path, if there is no such path vector is empty and distance std::numeric_limits<edge_type:weight_type>::max()
+ ///
+ /// \note TEdge of \p graph must follow graph::edge::WeightedEdge interface
+ /// \sa graph::edge_type::WeightedEdge
+ ///
+ /// \throws std::out_of_range if \p graph contains negative cycle
+ ///
+ template<typename TGraph, typename TNode, typename F = std::function<void(const TNode &,
+ const typename TGraph::edge_type::weight_type &)>>
+ static
+ ext::pair<ext::vector<TNode>, typename TGraph::edge_type::weight_type>
+ findPath(const TGraph &graph,
+ const TNode &start,
+ const TNode &goal,
+ F f_user = [](const TNode &,
+ const typename TGraph::edge_type::weight_type &) {});
+
+ template<typename TGraph, typename TNode>
+ static
+ ext::pair<ext::vector<TNode>, typename TGraph::edge_type::weight_type>
+ findPathRegistration(const TGraph &graph,
+ const TNode &start,
+ const TNode &goal) {
+ return findPath(graph, start, goal);
+ }
+
+// =====================================================================================================================
+ private:
+
+ template<typename TNode, typename TWeight>
+ struct Data {
+ std::deque<TNode> q; // queue
+ ext::map<TNode, TWeight> g; // distance (aka G score)
+ ext::map<TNode, TNode> p; // parents
+ ext::map<TNode, size_t> v; // visits
+ };
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+ template<typename TGraph, typename TNode, typename F>
+ static
+ Data<TNode, typename TGraph::edge_type::weight_type>
+ impl(const TGraph &graph,
+ const TNode &start,
+ F f_user);
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+ template<typename TNode, typename TWeight>
+ inline static void init(SPFA::Data<TNode, TWeight> &data, const TNode &start);
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+};
+
+// =====================================================================================================================
+
+template<typename TGraph, typename TNode, typename F>
+void SPFA::run(const TGraph &graph, const TNode &start, F f_user) {
+ impl(graph, start, f_user);
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+template<typename TGraph, typename TNode, typename F>
+ext::pair<ext::vector<TNode>, typename TGraph::edge_type::weight_type> SPFA::findPath(const TGraph &graph,
+ const TNode &start,
+ const TNode &goal,
+ F f_user) {
+ using weight_type = typename TGraph::edge_type::weight_type;
+
+ Data<TNode, weight_type> data = impl(graph, start, f_user);
+ return common::ReconstructPath::reconstructWeightedPath(data.p, data.g, start, goal);
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+template<typename TGraph, typename TNode, typename F>
+SPFA::Data<TNode, typename TGraph::edge_type::weight_type>
+SPFA::impl(const TGraph &graph, const TNode &start, F f_user) {
+ using weight_type = typename TGraph::edge_type::weight_type;
+
+ Data<TNode, weight_type> data;
+
+ auto nodes = graph.getNodes();
+ size_t nodes_cnt = nodes.size();
+
+ // Init data
+ init(data, start);
+
+ while (!data.q.empty()) {
+ TNode n = data.q.front();
+ data.q.pop_front();
+
+ ++data.v[n];
+
+ // Run user's function
+ f_user(n, data.g[n]);
+
+ if (data.v[n] >= nodes_cnt) {
+ throw std::out_of_range("SPFA: Detect negative cycle in graph.");
+ }
+
+ for (const auto &s_edge: graph.successorEdges(n)) {
+ const TNode &s = common::SupportFunction::other(s_edge, n); // successor
+
+ // Calculate new G score
+ weight_type gscore = data.g.at(n) + s_edge.weight();
+
+ // Search if the node s was already visited
+ auto search_d = data.g.find(s);
+
+ // If not or the distance can be improve do relaxation
+ if (search_d == data.g.end() || search_d->second > gscore) {
+
+ data.g[s] = gscore;
+ data.p.insert_or_assign(s, n);
+
+ // More effective than code below
+ data.q.push_back(s);
+ // Not effective at all
+// auto search_q = std::find(data.q.begin(), data.q.end(), s);
+// if (search_q == data.q.end()) {
+// data.q.push_back(s);
+// }
+ }
+ }
+ }
+
+ return data;
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+template<typename TNode, typename TWeight>
+void SPFA::init(SPFA::Data<TNode, TWeight> &data, const TNode &start) {
+ data.q.push_back(start);
+ data.v[start] = 1;
+ data.g[start] = 0;
+ data.p.insert_or_assign(start, start);
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+} // namespace shortest_path
+#endif //ALIB2_SPFA_HPP
--
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