demo/csp_demo.cc
author deba
Wed, 07 Mar 2007 12:00:59 +0000
changeset 2400 b199ded24c19
parent 2367 041878e6f388
child 2553 bfced05fa852
permissions -rw-r--r--
Steiner 2-approximation demo
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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) 2003-2007
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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 Demonstrating the usage of LEMON's algorithm for solving the
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/// Constrained shortest Path Problem 
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///
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/// \include csp_demo.cc
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#include <iostream>
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#include <lemon/list_graph.h>
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#include <lemon/csp.h>
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#include <lemon/random.h>
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using namespace lemon;
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int main (int, char*[])
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{
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    typedef ListGraph Graph;
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    typedef Graph::Node Node;
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    typedef Graph::Edge Edge;
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    typedef Graph::EdgeIt EdgeIt;
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    typedef Graph::EdgeMap<double> LengthMap;
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    Graph g;
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    const int N=100;
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    const int M=20000;
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    std::vector<Node> nodes;
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    std::vector<Edge> edges;
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    for(int i=0;i<N;i++) nodes.push_back(g.addNode());
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    for(int i=0;i<M;i++)
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      edges.push_back(g.addEdge(nodes[rnd[N]],nodes[rnd[N]]));
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    LengthMap cost(g);
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    LengthMap delay(g);
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    for(EdgeIt e(g);e!=INVALID;++e)
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      {
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	cost[e]=0.01+rnd(.99);
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	delay[e]=0.01+rnd(.99);
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      }
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    ConstrainedShortestPath<Graph,LengthMap,LengthMap> csp(g,cost,delay);
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    for(double d=0;d<2;d+=.001)
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      {
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	double lo_bo;
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	std::cout << d << ": ";
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	SimplePath<Graph> r = csp.larac(nodes[0],nodes[1],d,lo_bo);
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	if(r.empty()) std::cout << "INFEASIBLE\n";
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	else std::cout << "delay: " << csp.delay(r)
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		       << " cost: " << csp.cost(r)
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		       << " (lb: " << lo_bo
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		       << " gap: " << csp.cost(r)-lo_bo
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		       << " , " << (csp.cost(r)-lo_bo)/csp.cost(r)*100
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		       << "%)" << std::endl;
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      }
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    return 0;
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}