alpar@357: /* -*- C++ -*-
alpar@357:  *
alpar@357:  * This file is a part of LEMON, a generic C++ optimization library
alpar@357:  *
alpar@357:  * Copyright (C) 2003-2008
alpar@357:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@357:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@357:  *
alpar@357:  * Permission to use, modify and distribute this software is granted
alpar@357:  * provided that this copyright notice appears in all copies. For
alpar@357:  * precise terms see the accompanying LICENSE file.
alpar@357:  *
alpar@357:  * This software is provided "AS IS" with no warranty of any kind,
alpar@357:  * express or implied, and with no claim as to its suitability for any
alpar@357:  * purpose.
alpar@357:  *
alpar@357:  */
alpar@357: 
alpar@357: #include <iostream>
alpar@357: #include <fstream>
alpar@357: 
alpar@357: #include <lemon/list_graph.h>
alpar@357: #include <lemon/lgf_reader.h>
alpar@357: #include <lemon/path.h>
alpar@357: #include <lemon/suurballe.h>
alpar@357: 
alpar@357: #include "test_tools.h"
alpar@357: 
alpar@357: using namespace lemon;
alpar@357: 
kpeter@358: // Check the feasibility of the flow
alpar@357: template <typename Digraph, typename FlowMap>
alpar@357: bool checkFlow( const Digraph& gr, const FlowMap& flow, 
alpar@357:                 typename Digraph::Node s, typename Digraph::Node t,
alpar@357:                 int value )
alpar@357: {
alpar@357:   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
alpar@357:   for (ArcIt e(gr); e != INVALID; ++e)
alpar@357:     if (!(flow[e] == 0 || flow[e] == 1)) return false;
alpar@357: 
alpar@357:   for (NodeIt n(gr); n != INVALID; ++n) {
alpar@357:     int sum = 0;
alpar@357:     for (OutArcIt e(gr, n); e != INVALID; ++e)
alpar@357:       sum += flow[e];
alpar@357:     for (InArcIt e(gr, n); e != INVALID; ++e)
alpar@357:       sum -= flow[e];
alpar@357:     if (n == s && sum != value) return false;
alpar@357:     if (n == t && sum != -value) return false;
alpar@357:     if (n != s && n != t && sum != 0) return false;
alpar@357:   }
alpar@357: 
alpar@357:   return true;
alpar@357: }
alpar@357: 
kpeter@358: // Check the optimalitiy of the flow
alpar@357: template < typename Digraph, typename CostMap, 
alpar@357:            typename FlowMap, typename PotentialMap >
alpar@357: bool checkOptimality( const Digraph& gr, const CostMap& cost,
alpar@357:                       const FlowMap& flow, const PotentialMap& pi )
alpar@357: {
kpeter@358:   // Check the "Complementary Slackness" optimality condition
alpar@357:   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
alpar@357:   bool opt = true;
alpar@357:   for (ArcIt e(gr); e != INVALID; ++e) {
alpar@357:     typename CostMap::Value red_cost =
alpar@357:       cost[e] + pi[gr.source(e)] - pi[gr.target(e)];
alpar@357:     opt = (flow[e] == 0 && red_cost >= 0) ||
alpar@357:           (flow[e] == 1 && red_cost <= 0);
alpar@357:     if (!opt) break;
alpar@357:   }
alpar@357:   return opt;
alpar@357: }
alpar@357: 
kpeter@358: // Check a path
kpeter@358: template <typename Digraph, typename Path>
alpar@357: bool checkPath( const Digraph& gr, const Path& path,
alpar@357:                 typename Digraph::Node s, typename Digraph::Node t)
alpar@357: {
kpeter@358:   // Check the "Complementary Slackness" optimality condition
alpar@357:   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
alpar@357:   Node n = s;
alpar@357:   for (int i = 0; i < path.length(); ++i) {
alpar@357:     if (gr.source(path.nth(i)) != n) return false;
alpar@357:     n = gr.target(path.nth(i));
alpar@357:   }
alpar@357:   return n == t;
alpar@357: }
alpar@357: 
alpar@357: 
alpar@357: int main()
alpar@357: {
alpar@357:   DIGRAPH_TYPEDEFS(ListDigraph);
alpar@357: 
kpeter@358:   // Read the test digraph
alpar@357:   ListDigraph digraph;
alpar@357:   ListDigraph::ArcMap<int> length(digraph);
alpar@357:   Node source, target;
alpar@357: 
alpar@357:   std::string fname;
alpar@357:   if(getenv("srcdir"))
alpar@357:     fname = std::string(getenv("srcdir"));
alpar@357:   else fname = ".";
alpar@357:   fname += "/test/min_cost_flow_test.lgf";
alpar@357: 
alpar@357:   std::ifstream input(fname.c_str());
alpar@357:   check(input, "Input file '" << fname << "' not found");
alpar@357:   DigraphReader<ListDigraph>(digraph, input).
alpar@357:     arcMap("cost", length).
alpar@357:     node("source", source).
alpar@357:     node("target", target).
alpar@357:     run();
alpar@357:   input.close();
alpar@357:   
kpeter@358:   // Find 2 paths
alpar@357:   {
alpar@357:     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
alpar@357:     check(suurballe.run(2) == 2, "Wrong number of paths");
alpar@357:     check(checkFlow(digraph, suurballe.flowMap(), source, target, 2),
alpar@357:           "The flow is not feasible");
alpar@357:     check(suurballe.totalLength() == 510, "The flow is not optimal");
alpar@357:     check(checkOptimality(digraph, length, suurballe.flowMap(), 
alpar@357:                           suurballe.potentialMap()),
alpar@357:           "Wrong potentials");
alpar@357:     for (int i = 0; i < suurballe.pathNum(); ++i)
alpar@357:       check(checkPath(digraph, suurballe.path(i), source, target),
alpar@357:             "Wrong path");
alpar@357:   }
alpar@357: 
kpeter@358:   // Find 3 paths
alpar@357:   {
alpar@357:     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
alpar@357:     check(suurballe.run(3) == 3, "Wrong number of paths");
alpar@357:     check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
alpar@357:           "The flow is not feasible");
alpar@357:     check(suurballe.totalLength() == 1040, "The flow is not optimal");
alpar@357:     check(checkOptimality(digraph, length, suurballe.flowMap(), 
alpar@357:                           suurballe.potentialMap()),
alpar@357:           "Wrong potentials");
alpar@357:     for (int i = 0; i < suurballe.pathNum(); ++i)
alpar@357:       check(checkPath(digraph, suurballe.path(i), source, target),
alpar@357:             "Wrong path");
alpar@357:   }
alpar@357: 
kpeter@358:   // Find 5 paths (only 3 can be found)
alpar@357:   {
alpar@357:     Suurballe<ListDigraph> suurballe(digraph, length, source, target);
alpar@357:     check(suurballe.run(5) == 3, "Wrong number of paths");
alpar@357:     check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
alpar@357:           "The flow is not feasible");
alpar@357:     check(suurballe.totalLength() == 1040, "The flow is not optimal");
alpar@357:     check(checkOptimality(digraph, length, suurballe.flowMap(), 
alpar@357:                           suurballe.potentialMap()),
alpar@357:           "Wrong potentials");
alpar@357:     for (int i = 0; i < suurballe.pathNum(); ++i)
alpar@357:       check(checkPath(digraph, suurballe.path(i), source, target),
alpar@357:             "Wrong path");
alpar@357:   }
alpar@357: 
alpar@357:   return 0;
alpar@357: }