demo/steiner_demo.cc
author kpeter
Sun, 13 Jan 2008 10:26:55 +0000
changeset 2555 a84e52e99f57
parent 2492 387f6ff851ef
child 2569 12c2c5c4330b
permissions -rw-r--r--
Reimplemented MinMeanCycle to be much more efficient.
The new version implements Howard's algorithm instead of Karp's algorithm and
it is at least 10-20 times faster on all the 40-50 random graphs we have tested.
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/* -*- C++ -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2003-2008
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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///\ingroup demos
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///\file
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///\brief Calculating an approximate Steiner-tree.
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///
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/// Calculating an approximate Steiner-tree.
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///
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/// \include steiner_demo.cc
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#include <lemon/smart_graph.h>
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#include <lemon/kruskal.h>
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#include <lemon/graph_reader.h>
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#include <lemon/time_measure.h>
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#include <lemon/graph_to_eps.h>
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#include <lemon/steiner.h>
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#include <cstdlib>
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#include <cmath>
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using namespace lemon;
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using namespace lemon::dim2;
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using namespace std;
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int main(int argc, const char *argv[]) {
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  std::string lgf = argc > 1 ? argv[1] : "steiner.lgf";
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  std::string eps = argc > 2 ? argv[2] : "steiner.eps";
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  SmartUGraph graph;
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  SmartUGraph::NodeMap<bool> terminal(graph);
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  SmartUGraph::NodeMap<int> label(graph);
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  SmartUGraph::NodeMap<Point<double> > coord(graph);
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  UGraphReader<SmartUGraph>(lgf, graph).
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    readNodeMap("coordinates_x", xMap(coord)).
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    readNodeMap("coordinates_y", yMap(coord)).
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    readNodeMap("terminal", terminal).run();
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  SmartUGraph::UEdgeMap<double> cost(graph);
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  for (SmartUGraph::UEdgeIt it(graph); it != INVALID; ++it) {
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    cost[it] = sqrt((coord[graph.target(it)] - 
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                     coord[graph.source(it)]).normSquare());
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  }
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  SteinerTree<SmartUGraph> steiner(graph, cost);
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  steiner.init();
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  for (SmartUGraph::NodeIt it(graph); it != INVALID; ++it) {
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    if (terminal[it]) {
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      steiner.addTerminal(it);
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    }
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  }
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  steiner.start();
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  Palette nodepalette(0);
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  nodepalette.add(Color(1.0, 1.0, 1.0));
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  nodepalette.add(Color(0.0, 1.0, 0.0));
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  nodepalette.add(Color(0.5, 0.5, 0.5));
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  SmartUGraph::NodeMap<int> nodecolor(graph);
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  for (SmartUGraph::NodeIt it(graph); it != INVALID; ++it) {
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    if (steiner.terminal(it)) {
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      nodecolor[it] = 1;
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    } else if (steiner.steiner(it)) {
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      nodecolor[it] = 2;
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    } else {
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      nodecolor[it] = 0;
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    }
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  }
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  Palette edgepalette(0);
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  edgepalette.add(Color(0.0, 0.0, 0.0));
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  edgepalette.add(Color(1.0, 0.0, 0.0));
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  SmartUGraph::UEdgeMap<int> edgecolor(graph);
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  for (SmartUGraph::UEdgeIt it(graph); it != INVALID; ++it) {
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    edgecolor[it] = steiner.tree(it) ? 1 : 0;
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  }
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  graphToEps(graph, eps).
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    coords(coord).undirected().
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    nodeScale(1.0).scaleToA4().
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    nodeColors(composeMap(nodepalette, nodecolor)).
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    edgeColors(composeMap(edgepalette, edgecolor)).
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    nodeTexts(label).nodeTextSize(8).run();
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  std::cout << "The tree constructed: " << eps << std::endl;
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  std::cout << "The cost of the tree: " << steiner.treeValue() << std::endl;
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  return 0;
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}