add brute force algorithm for tsp for small tests

routing_algorithms/tsp_brute_force.hpp

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+/*
+
+Copyright (c) 2015, Project OSRM contributors
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this list
+of conditions and the following disclaimer.
+Redistributions in binary form must reproduce the above copyright notice, this
+list of conditions and the following disclaimer in the documentation and/or
+other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+#ifndef TSP_BRUTE_FORCE_HPP
+#define TSP_BRUTE_FORCE_HPP
+
+
+#include "../data_structures/search_engine.hpp"
+#include "../util/string_util.hpp"
+
+#include <osrm/json_container.hpp>
+
+#include <cstdlib>
+
+#include <algorithm>
+#include <string>
+#include <vector>
+#include <limits>
+#include "../util/simple_logger.hpp"
+
+
+// HAHAHA. NICE TRY, CHAU.
+
+
+namespace osrm
+{
+namespace tsp
+{
+void BruteForce(const RouteParameters & route_parameters,
+                const PhantomNodeArray & phantom_node_vector,
+                const std::vector<EdgeWeight> & dist_table,
+                InternalRouteResult & min_route,
+                std::vector<int> & min_loc_permutation) {
+
+    const auto number_of_locations = phantom_node_vector.size();
+    std::vector<int> location_ids(number_of_locations);
+    std::iota(location_ids.begin(), location_ids.end(), 0);
+
+    int min_route_dist = std::numeric_limits<int>::max();
+    do {
+        int route_dist = 0;
+        for (int i = 0; i < number_of_locations - 1; ++i) {
+            route_dist += *(dist_table.begin() + (location_ids[i] * number_of_locations) + location_ids[i+1]);
+        }
+        route_dist += *(dist_table.begin() + (location_ids[number_of_locations-1] * number_of_locations) + location_ids[0]);
+
+        if (route_dist < min_route_dist) {
+            min_route_dist = route_dist;
+            //TODO: this gets copied right? fix this
+            min_loc_permutation = location_ids;
+        }
+    } while(std::next_permutation(location_ids.begin(), location_ids.end()));
+
+    PhantomNodes viapoint;
+    for (int i = 0; i < number_of_locations - 1; ++i) {
+        viapoint = PhantomNodes{phantom_node_vector[i][0], phantom_node_vector[i + 1][0]};
+        min_route.segment_end_coordinates.emplace_back(viapoint);
+    }
+    viapoint = PhantomNodes{phantom_node_vector[number_of_locations - 1][0], phantom_node_vector[0][0]};
+    min_route.segment_end_coordinates.emplace_back(viapoint);
+}
+
+}
+}
+#endif // TSP_BRUTE_FORCE_HPP