74e00cf652
remove empty unit test remove compiler directives move trip related files from routing_algorithms to algorithms run clang-format on files fix all std::size_t related issues improve code by adding std::move()s clean up includes fixing several code stye and improvement issues add several small code improvements return single scc in SplitUnaccessibleLocations() when theres only one change ComputeRoute() to return an InternalRouteResult by value improve some code style issues
122 lines
4.6 KiB
C++
122 lines
4.6 KiB
C++
/*
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Copyright (c) 2015, Project OSRM contributors
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All rights reserved.
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Redistribution and use in source and binary forms, with or without modification,
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are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this list
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of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright notice, this
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list of conditions and the following disclaimer in the documentation and/or
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other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TRIP_NEAREST_NEIGHBOUR_HPP
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#define TRIP_NEAREST_NEIGHBOUR_HPP
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#include "../data_structures/search_engine.hpp"
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#include "../util/simple_logger.hpp"
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#include "../util/dist_table_wrapper.hpp"
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#include <osrm/json_container.hpp>
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#include <cstdlib>
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#include <algorithm>
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#include <string>
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#include <vector>
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#include <limits>
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namespace osrm
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{
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namespace trip
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{
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template <typename NodeIDIterator>
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std::vector<NodeID> NearestNeighbourTrip(const NodeIDIterator &start,
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const NodeIDIterator &end,
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const std::size_t number_of_locations,
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const DistTableWrapper<EdgeWeight> &dist_table)
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{
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//////////////////////////////////////////////////////////////////////////////////////////////////
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// START GREEDY NEAREST NEIGHBOUR HERE
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// 1. grab a random location and mark as starting point
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// 2. find the nearest unvisited neighbour, set it as the current location and mark as visited
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// 3. repeat 2 until there is no unvisited location
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// 4. return route back to starting point
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// 5. compute route
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// 6. repeat 1-5 with different starting points and choose iteration with shortest trip
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// 7. DONE!
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//////////////////////////////////////////////////////////////////////////////////////////////////
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std::vector<NodeID> route;
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route.reserve(number_of_locations);
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const auto component_size = std::distance(start, end);
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auto shortest_trip_distance = INVALID_EDGE_WEIGHT;
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// ALWAYS START AT ANOTHER STARTING POINT
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for (auto start_node = start; start_node != end; ++start_node)
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{
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NodeID curr_node = *start_node;
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std::vector<NodeID> curr_route;
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curr_route.reserve(component_size);
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curr_route.push_back(*start_node);
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// visited[i] indicates whether node i was already visited by the salesman
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std::vector<bool> visited(number_of_locations, false);
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visited[*start_node] = true;
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// 3. REPEAT FOR EVERY UNVISITED NODE
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EdgeWeight trip_dist = 0;
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for (std::size_t via_point = 1; via_point < component_size; ++via_point)
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{
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EdgeWeight min_dist = INVALID_EDGE_WEIGHT;
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NodeID min_id = SPECIAL_NODEID;
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// 2. FIND NEAREST NEIGHBOUR
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for (auto next = start; next != end; ++next)
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{
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const auto curr_dist = dist_table(curr_node, *next);
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BOOST_ASSERT_MSG(curr_dist != INVALID_EDGE_WEIGHT, "invalid distance found");
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if (!visited[*next] && curr_dist < min_dist)
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{
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min_dist = curr_dist;
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min_id = *next;
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}
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}
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BOOST_ASSERT_MSG(min_id != SPECIAL_NODEID, "no next node found");
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visited[min_id] = true;
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curr_route.push_back(min_id);
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trip_dist += min_dist;
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curr_node = min_id;
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}
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// check round trip with this starting point is shorter than the shortest round trip found
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// till now
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if (trip_dist < shortest_trip_distance)
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{
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shortest_trip_distance = trip_dist;
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route = std::move(curr_route);
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}
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}
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return route;
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}
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} // end namespace trip
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} // end namespace osrm
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#endif // TRIP_NEAREST_NEIGHBOUR_HPP
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