test/suurballe_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Fri, 28 Nov 2008 06:38:20 +0000
changeset 387 24a2c6ee6cb0
parent 345 2f64c4a692a8
child 423 ff48c2738fb2
permissions -rw-r--r--
Refactoring of DIMACS tools
     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2008
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 #include <iostream>
    20 #include <fstream>
    21 
    22 #include <lemon/list_graph.h>
    23 #include <lemon/lgf_reader.h>
    24 #include <lemon/path.h>
    25 #include <lemon/suurballe.h>
    26 
    27 #include "test_tools.h"
    28 
    29 using namespace lemon;
    30 
    31 // Check the feasibility of the flow
    32 template <typename Digraph, typename FlowMap>
    33 bool checkFlow( const Digraph& gr, const FlowMap& flow, 
    34                 typename Digraph::Node s, typename Digraph::Node t,
    35                 int value )
    36 {
    37   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
    38   for (ArcIt e(gr); e != INVALID; ++e)
    39     if (!(flow[e] == 0 || flow[e] == 1)) return false;
    40 
    41   for (NodeIt n(gr); n != INVALID; ++n) {
    42     int sum = 0;
    43     for (OutArcIt e(gr, n); e != INVALID; ++e)
    44       sum += flow[e];
    45     for (InArcIt e(gr, n); e != INVALID; ++e)
    46       sum -= flow[e];
    47     if (n == s && sum != value) return false;
    48     if (n == t && sum != -value) return false;
    49     if (n != s && n != t && sum != 0) return false;
    50   }
    51 
    52   return true;
    53 }
    54 
    55 // Check the optimalitiy of the flow
    56 template < typename Digraph, typename CostMap, 
    57            typename FlowMap, typename PotentialMap >
    58 bool checkOptimality( const Digraph& gr, const CostMap& cost,
    59                       const FlowMap& flow, const PotentialMap& pi )
    60 {
    61   // Check the "Complementary Slackness" optimality condition
    62   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
    63   bool opt = true;
    64   for (ArcIt e(gr); e != INVALID; ++e) {
    65     typename CostMap::Value red_cost =
    66       cost[e] + pi[gr.source(e)] - pi[gr.target(e)];
    67     opt = (flow[e] == 0 && red_cost >= 0) ||
    68           (flow[e] == 1 && red_cost <= 0);
    69     if (!opt) break;
    70   }
    71   return opt;
    72 }
    73 
    74 // Check a path
    75 template <typename Digraph, typename Path>
    76 bool checkPath( const Digraph& gr, const Path& path,
    77                 typename Digraph::Node s, typename Digraph::Node t)
    78 {
    79   // Check the "Complementary Slackness" optimality condition
    80   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
    81   Node n = s;
    82   for (int i = 0; i < path.length(); ++i) {
    83     if (gr.source(path.nth(i)) != n) return false;
    84     n = gr.target(path.nth(i));
    85   }
    86   return n == t;
    87 }
    88 
    89 
    90 int main()
    91 {
    92   DIGRAPH_TYPEDEFS(ListDigraph);
    93 
    94   // Read the test digraph
    95   ListDigraph digraph;
    96   ListDigraph::ArcMap<int> length(digraph);
    97   Node source, target;
    98 
    99   std::string fname;
   100   if(getenv("srcdir"))
   101     fname = std::string(getenv("srcdir"));
   102   else fname = ".";
   103   fname += "/test/min_cost_flow_test.lgf";
   104 
   105   std::ifstream input(fname.c_str());
   106   check(input, "Input file '" << fname << "' not found");
   107   DigraphReader<ListDigraph>(digraph, input).
   108     arcMap("cost", length).
   109     node("source", source).
   110     node("target", target).
   111     run();
   112   input.close();
   113   
   114   // Find 2 paths
   115   {
   116     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
   117     check(suurballe.run(2) == 2, "Wrong number of paths");
   118     check(checkFlow(digraph, suurballe.flowMap(), source, target, 2),
   119           "The flow is not feasible");
   120     check(suurballe.totalLength() == 510, "The flow is not optimal");
   121     check(checkOptimality(digraph, length, suurballe.flowMap(), 
   122                           suurballe.potentialMap()),
   123           "Wrong potentials");
   124     for (int i = 0; i < suurballe.pathNum(); ++i)
   125       check(checkPath(digraph, suurballe.path(i), source, target),
   126             "Wrong path");
   127   }
   128 
   129   // Find 3 paths
   130   {
   131     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
   132     check(suurballe.run(3) == 3, "Wrong number of paths");
   133     check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
   134           "The flow is not feasible");
   135     check(suurballe.totalLength() == 1040, "The flow is not optimal");
   136     check(checkOptimality(digraph, length, suurballe.flowMap(), 
   137                           suurballe.potentialMap()),
   138           "Wrong potentials");
   139     for (int i = 0; i < suurballe.pathNum(); ++i)
   140       check(checkPath(digraph, suurballe.path(i), source, target),
   141             "Wrong path");
   142   }
   143 
   144   // Find 5 paths (only 3 can be found)
   145   {
   146     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
   147     check(suurballe.run(5) == 3, "Wrong number of paths");
   148     check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
   149           "The flow is not feasible");
   150     check(suurballe.totalLength() == 1040, "The flow is not optimal");
   151     check(checkOptimality(digraph, length, suurballe.flowMap(), 
   152                           suurballe.potentialMap()),
   153           "Wrong potentials");
   154     for (int i = 0; i < suurballe.pathNum(); ++i)
   155       check(checkPath(digraph, suurballe.path(i), source, target),
   156             "Wrong path");
   157   }
   158 
   159   return 0;
   160 }