71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
//=======================================================================
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// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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#include <iostream>
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#include <boost/graph/edge_list.hpp>
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#include <boost/graph/bellman_ford_shortest_paths.hpp>
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int main()
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{
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using namespace boost;
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// ID numbers for the routers (vertices).
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enum
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{
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A,
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B,
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C,
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D,
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E,
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F,
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G,
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H,
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n_vertices
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};
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const int n_edges = 11;
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typedef std::pair< int, int > Edge;
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// The list of connections between routers stored in an array.
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Edge edges[] = { Edge(A, B), Edge(A, C), Edge(B, D), Edge(B, E), Edge(C, E),
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Edge(C, F), Edge(D, H), Edge(D, E), Edge(E, H), Edge(F, G),
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Edge(G, H) };
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// Specify the graph type and declare a graph object
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typedef edge_list< Edge*, Edge, std::ptrdiff_t,
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std::random_access_iterator_tag >
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Graph;
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Graph g(edges, edges + n_edges);
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// The transmission delay values for each edge.
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float delay[] = { 5.0, 1.0, 1.3, 3.0, 10.0, 2.0, 6.3, 0.4, 1.3, 1.2, 0.5 };
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// Declare some storage for some "external" vertex properties.
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char name[] = "ABCDEFGH";
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int parent[n_vertices];
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for (int i = 0; i < n_vertices; ++i)
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parent[i] = i;
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float distance[n_vertices];
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std::fill(
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distance, distance + n_vertices, (std::numeric_limits< float >::max)());
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// Specify A as the source vertex
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distance[A] = 0;
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bool r = bellman_ford_shortest_paths(g, int(n_vertices),
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weight_map(
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make_iterator_property_map(&delay[0], get(edge_index, g), delay[0]))
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.distance_map(&distance[0])
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.predecessor_map(&parent[0]));
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if (r)
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for (int i = 0; i < n_vertices; ++i)
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std::cout << name[i] << ": " << distance[i] << " "
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<< name[parent[i]] << std::endl;
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else
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std::cout << "negative cycle" << std::endl;
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return EXIT_SUCCESS;
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}
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