Add Greedy-Best-First search.

alib2graph_algo/src/shortest_path/GreedyBestFS.cpp

+// GreedyBestFS.cpp
+//
+//     Created on: 21. 02. 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 "GreedyBestFS.hpp"
+
+#include <registration/AlgoRegistration.hpp>
+
+namespace {
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+auto GreedyBestFS1 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedUndirectedGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFS2 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedUndirectedMultiGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFS3 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedDirectedGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFS4 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedDirectedMultiGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFS5 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedMixedGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFS6 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                    ext::pair<ext::vector<DefaultNodeType>, DefaultWeightType>,
+                                                    const graph::WeightedMixedMultiGraph<> &,
+                                                    const DefaultNodeType &,
+                                                    const DefaultNodeType &,
+                                                    std::function<DefaultWeightType(const DefaultNodeType &,
+                                                                                    const DefaultNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFSGrid1 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                        ext::pair<ext::vector<DefaultSquareGridNodeType>,
+                                                                  DefaultWeightType>,
+                                                        const grid::WeightedSquareGrid4<> &,
+                                                        const DefaultSquareGridNodeType &,
+                                                        const DefaultSquareGridNodeType &,
+                                                        std::function<DefaultWeightType(const DefaultSquareGridNodeType &,
+                                                                                        const DefaultSquareGridNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+auto GreedyBestFSGrid2 = registration::AbstractRegister<shortest_path::GreedyBestFS,
+                                                        ext::pair<ext::vector<DefaultSquareGridNodeType>,
+                                                                  DefaultWeightType>,
+                                                        const grid::WeightedSquareGrid8<> &,
+                                                        const DefaultSquareGridNodeType &,
+                                                        const DefaultSquareGridNodeType &,
+                                                        std::function<DefaultWeightType(const DefaultSquareGridNodeType &,
+                                                                                        const DefaultSquareGridNodeType &)> >(
+    shortest_path::GreedyBestFS::findPathRegistration);
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+}

alib2graph_algo/src/shortest_path/GreedyBestFS.hpp

+// GreedyBestFS.hpp
+//
+//     Created on: 21. 02. 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_GREEDYBESTFS_HPP
+#define ALIB2_GREEDYBESTFS_HPP
+
+#include <functional>
+#include <alib/vector>
+#include <alib/pair>
+#include <alib/set>
+#include <alib/map>
+
+#include <common/ReconstructPath.hpp>
+#include <common/SupportFunction.hpp>
+
+namespace shortest_path {
+
+class GreedyBestFS {
+// ---------------------------------------------------------------------------------------------------------------------
+
+ public:
+
+  /// Find the shortest path using Greedy Best-first search algorithm from the \p start node to the \p goal node in the \p graph.
+  /// \note The founded path is not necessary the optimal one.
+  ///
+  /// 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_heuristic heuristic function which accept node and return edge_type::weight_type.
+  /// \param f_user function which is called for every opened 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 an edge with a negative weight.
+  ///
+  template<
+      typename TGraph,
+      typename TNode,
+      typename F1 = std::function<typename TGraph::edge_type::weight_type(const TNode &)>,
+      typename F2 = 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,
+           F1 f_heuristic,
+           F2 f_user = [](const TNode &,
+                          const typename TGraph::edge_type::weight_type &) {});
+
+  template<
+      typename TGraph,
+      typename TNode,
+      typename F1 = std::function<typename TGraph::edge_type::weight_type(const TNode &, const TNode &)>
+  >
+  static
+  ext::pair<ext::vector<TNode>, typename TGraph::edge_type::weight_type>
+  findPathRegistration(const TGraph &graph,
+                       const TNode &start,
+                       const TNode &goal,
+                       F1 f_heuristic) {
+    return findPath(graph, start, goal, [&](const TNode &n) { return f_heuristic(goal, n); });
+  }
+
+// =====================================================================================================================
+
+ private:
+
+  template<typename TNode, typename TWeight>
+  struct Data {
+    ext::set<ext::pair<TWeight, TNode>> queue; // priority queue
+    ext::map<TNode, TWeight> g; // G score
+    ext::map<TNode, TNode> p; // parents
+  };
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+  template<typename FEdges, typename TNode, typename TWeight, typename F1, typename F2, typename F3>
+  static bool relaxation(FEdges successor_edges,
+                         Data<TNode, TWeight> &data,
+                         F1 f_heuristic,
+                         F2 f_user,
+                         F3 f_stop);
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+  template<typename TNode, typename TWeight, typename F>
+  inline static void init(GreedyBestFS::Data<TNode, TWeight> &data, const TNode &start, F f_heuristic);
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+};
+
+// =====================================================================================================================
+
+template<typename TGraph, typename TNode, typename F1, typename F2>
+ext::pair<ext::vector<TNode>, typename TGraph::edge_type::weight_type>
+GreedyBestFS::findPath(const TGraph &graph,
+                       const TNode &start,
+                       const TNode &goal,
+                       F1 f_heuristic,
+                       F2 f_user) {
+  using weight_type = typename TGraph::edge_type::weight_type;
+
+  Data<TNode, weight_type> data;
+
+  // Init search
+  init(data, start, f_heuristic);
+
+  while (!data.queue.empty()) {
+    bool stop = relaxation([&](const auto &node) -> auto { return graph.successorEdges(node); },
+                           data,
+                           f_heuristic,
+                           f_user,
+                           [&goal](const TNode &n) -> bool { return goal == n; });
+
+    if (stop) {
+      break;
+    }
+  }
+
+  return common::ReconstructPath::reconstructWeightedPath(data.p, data.g, start, goal);
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+template<typename FEdges, typename TNode, typename TWeight, typename F1, typename F2, typename F3>
+bool
+GreedyBestFS::relaxation(FEdges successor_edges,
+                         GreedyBestFS::Data<TNode, TWeight> &data,
+                         F1 f_heuristic,
+                         F2 f_user,
+                         F3 f_stop) {
+  TNode n = data.queue.begin()->second;
+  data.queue.erase(data.queue.begin());
+
+  // Run user's function
+  f_user(n, data.g[n]);
+
+  // Stop if reach the goal
+  if (f_stop(n)) {
+    return true;
+  }
+
+  for (const auto &s_edge: successor_edges(n)) {
+    const TNode &s = common::SupportFunction::other(s_edge, n); // successor
+
+    // Check for negative edge
+    if (s_edge.weight() < 0) {
+      throw std::out_of_range("GreedyBestFS: Detect negative weight on edge in graph.");
+    }
+
+    // Calculate new G score
+    TWeight gscore = data.g.at(n) + s_edge.weight();
+
+    // Search if the node s was already visited
+    auto search_g = data.g.find(s);
+
+    // If not or the G score can be improve do relaxation
+    if (search_g == data.g.end() || data.g.at(s) > gscore) {
+      data.g[s] = gscore;
+      data.p.insert_or_assign(s, n);
+      if (search_g == data.g.end()) {
+        data.queue.insert(ext::make_pair(f_heuristic(s), s));
+      }
+    }
+  }
+
+  return false;
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+template<typename TNode, typename TWeight, typename F>
+void GreedyBestFS::init(GreedyBestFS::Data<TNode, TWeight> &data, const TNode &start, F f_heuristic) {
+  data.g[start] = 0;
+  data.p.insert_or_assign(start, start);
+  data.queue.insert(ext::make_pair(f_heuristic(start), start));
+}
+
+// ---------------------------------------------------------------------------------------------------------------------
+
+} // namespace shortest_path
+#endif //ALIB2_GREEDYBESTFS_HPP