980e4ee89a
This is true:
-1 > 1u
because the integer literal `-1` is first converted to a large unsigned
value and then compared to the unsigned `1`.
This patch fixes several of those isses in the farthest insertion
algorithm.
`-Wsign-compare` catches those issues.
References:
- http://stackoverflow.com/a/5416498
- C++14 standard
216 lines
8.2 KiB
C++
216 lines
8.2 KiB
C++
/*
|
|
|
|
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 TRIP_FARTHEST_INSERTION_HPP
|
|
#define TRIP_FARTHEST_INSERTION_HPP
|
|
|
|
#include "../data_structures/search_engine.hpp"
|
|
#include "../util/dist_table_wrapper.hpp"
|
|
|
|
#include <osrm/json_container.hpp>
|
|
#include <boost/assert.hpp>
|
|
|
|
#include <cstdlib>
|
|
#include <algorithm>
|
|
#include <string>
|
|
#include <vector>
|
|
#include <limits>
|
|
|
|
namespace osrm
|
|
{
|
|
namespace trip
|
|
{
|
|
|
|
// given a route and a new location, find the best place of insertion and
|
|
// check the distance of roundtrip when the new location is additionally visited
|
|
using NodeIDIter = std::vector<NodeID>::iterator;
|
|
std::pair<EdgeWeight, NodeIDIter>
|
|
GetShortestRoundTrip(const NodeID new_loc,
|
|
const DistTableWrapper<EdgeWeight> &dist_table,
|
|
const std::size_t number_of_locations,
|
|
std::vector<NodeID> &route)
|
|
{
|
|
|
|
auto min_trip_distance = INVALID_EDGE_WEIGHT;
|
|
NodeIDIter next_insert_point_candidate;
|
|
|
|
// for all nodes in the current trip find the best insertion resulting in the shortest path
|
|
// assert min 2 nodes in route
|
|
const auto start = std::begin(route);
|
|
const auto end = std::end(route);
|
|
for (auto from_node = start; from_node != end; ++from_node)
|
|
{
|
|
auto to_node = std::next(from_node);
|
|
if (to_node == end)
|
|
{
|
|
to_node = start;
|
|
}
|
|
|
|
const auto dist_from = dist_table(*from_node, new_loc);
|
|
const auto dist_to = dist_table(new_loc, *to_node);
|
|
const auto trip_dist = dist_from + dist_to - dist_table(*from_node, *to_node);
|
|
|
|
BOOST_ASSERT_MSG(dist_from != INVALID_EDGE_WEIGHT, "distance has invalid edge weight");
|
|
BOOST_ASSERT_MSG(dist_to != INVALID_EDGE_WEIGHT, "distance has invalid edge weight");
|
|
BOOST_ASSERT_MSG(trip_dist >= 0, "previous trip was not minimal. something's wrong");
|
|
|
|
// from all possible insertions to the current trip, choose the shortest of all insertions
|
|
if (trip_dist < min_trip_distance)
|
|
{
|
|
min_trip_distance = trip_dist;
|
|
next_insert_point_candidate = to_node;
|
|
}
|
|
}
|
|
BOOST_ASSERT_MSG(min_trip_distance != INVALID_EDGE_WEIGHT, "trip has invalid edge weight");
|
|
|
|
return std::make_pair(min_trip_distance, next_insert_point_candidate);
|
|
}
|
|
|
|
template <typename NodeIDIterator>
|
|
// given two initial start nodes, find a roundtrip route using the farthest insertion algorithm
|
|
std::vector<NodeID> FindRoute(const std::size_t &number_of_locations,
|
|
const std::size_t &component_size,
|
|
const NodeIDIterator &start,
|
|
const NodeIDIterator &end,
|
|
const DistTableWrapper<EdgeWeight> &dist_table,
|
|
const NodeID &start1,
|
|
const NodeID &start2)
|
|
{
|
|
BOOST_ASSERT_MSG(number_of_locations >= component_size,
|
|
"component size bigger than total number of locations");
|
|
|
|
std::vector<NodeID> route;
|
|
route.reserve(number_of_locations);
|
|
|
|
// tracks which nodes have been already visited
|
|
std::vector<bool> visited(number_of_locations, false);
|
|
|
|
visited[start1] = true;
|
|
visited[start2] = true;
|
|
route.push_back(start1);
|
|
route.push_back(start2);
|
|
|
|
// add all other nodes missing (two nodes are already in the initial start trip)
|
|
for (std::size_t j = 2; j < component_size; ++j)
|
|
{
|
|
|
|
auto farthest_distance = 0;
|
|
auto next_node = -1;
|
|
NodeIDIter next_insert_point;
|
|
|
|
// find unvisited loc i that is the farthest away from all other visited locs
|
|
for (auto i = start; i != end; ++i)
|
|
{
|
|
// find the shortest distance from i to all visited nodes
|
|
if (!visited[*i])
|
|
{
|
|
const auto insert_candidate =
|
|
GetShortestRoundTrip(*i, dist_table, number_of_locations, route);
|
|
|
|
BOOST_ASSERT_MSG(insert_candidate.first != INVALID_EDGE_WEIGHT,
|
|
"shortest round trip is invalid");
|
|
|
|
// add the location to the current trip such that it results in the shortest total
|
|
// tour
|
|
if (insert_candidate.first >= farthest_distance)
|
|
{
|
|
farthest_distance = insert_candidate.first;
|
|
next_node = *i;
|
|
next_insert_point = insert_candidate.second;
|
|
}
|
|
}
|
|
}
|
|
|
|
BOOST_ASSERT_MSG(next_node >= 0, "next node to visit is invalid");
|
|
|
|
// mark as visited and insert node
|
|
visited[next_node] = true;
|
|
route.insert(next_insert_point, next_node);
|
|
}
|
|
return route;
|
|
}
|
|
|
|
template <typename NodeIDIterator>
|
|
std::vector<NodeID> FarthestInsertionTrip(const NodeIDIterator &start,
|
|
const NodeIDIterator &end,
|
|
const std::size_t number_of_locations,
|
|
const DistTableWrapper<EdgeWeight> &dist_table)
|
|
{
|
|
//////////////////////////////////////////////////////////////////////////////////////////////////
|
|
// START FARTHEST INSERTION HERE
|
|
// 1. start at a random round trip of 2 locations
|
|
// 2. find the location that is the farthest away from the visited locations and whose insertion
|
|
// will make the round trip the longest
|
|
// 3. add the found location to the current round trip such that round trip is the shortest
|
|
// 4. repeat 2-3 until all locations are visited
|
|
// 5. DONE!
|
|
//////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
const auto component_size = std::distance(start, end);
|
|
BOOST_ASSERT(component_size >= 0);
|
|
|
|
auto max_from = -1;
|
|
auto max_to = -1;
|
|
|
|
if (static_cast<std::size_t>(component_size) == number_of_locations)
|
|
{
|
|
// find the pair of location with the biggest distance and make the pair the initial start
|
|
// trip
|
|
const auto index = std::distance(
|
|
std::begin(dist_table), std::max_element(std::begin(dist_table), std::end(dist_table)));
|
|
max_from = index / number_of_locations;
|
|
max_to = index % number_of_locations;
|
|
}
|
|
else
|
|
{
|
|
auto max_dist = 0;
|
|
for (auto x = start; x != end; ++x)
|
|
{
|
|
for (auto y = start; y != end; ++y)
|
|
{
|
|
const auto xy_dist = dist_table(*x, *y);
|
|
if (xy_dist > max_dist)
|
|
{
|
|
max_dist = xy_dist;
|
|
max_from = *x;
|
|
max_to = *y;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
BOOST_ASSERT(max_from >= 0);
|
|
BOOST_ASSERT(max_to >= 0);
|
|
BOOST_ASSERT_MSG(static_cast<std::size_t>(max_from) < number_of_locations, "start node");
|
|
BOOST_ASSERT_MSG(static_cast<std::size_t>(max_to) < number_of_locations, "start node");
|
|
return FindRoute(number_of_locations, component_size, start, end, dist_table, max_from, max_to);
|
|
}
|
|
|
|
} // end namespace trip
|
|
} // end namespace osrm
|
|
|
|
#endif // TRIP_FARTHEST_INSERTION_HPP
|