test/preflow_test.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Tue, 15 Mar 2011 17:59:57 +0100
changeset 934 fe283caf6414
parent 877 141f9c0db4a3
parent 923 30d5f950aa5f
child 1008 d216e1c8b3fa
permissions -rw-r--r--
Minor improvements in CostScaling (#417)
     1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library.
     4  *
     5  * Copyright (C) 2003-2010
     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 
    21 #include "test_tools.h"
    22 #include <lemon/smart_graph.h>
    23 #include <lemon/preflow.h>
    24 #include <lemon/concepts/digraph.h>
    25 #include <lemon/concepts/maps.h>
    26 #include <lemon/lgf_reader.h>
    27 #include <lemon/elevator.h>
    28 
    29 using namespace lemon;
    30 
    31 char test_lgf[] =
    32   "@nodes\n"
    33   "label\n"
    34   "0\n"
    35   "1\n"
    36   "2\n"
    37   "3\n"
    38   "4\n"
    39   "5\n"
    40   "6\n"
    41   "7\n"
    42   "8\n"
    43   "9\n"
    44   "@arcs\n"
    45   "    label capacity\n"
    46   "0 1 0     20\n"
    47   "0 2 1     0\n"
    48   "1 1 2     3\n"
    49   "1 2 3     8\n"
    50   "1 3 4     8\n"
    51   "2 5 5     5\n"
    52   "3 2 6     5\n"
    53   "3 5 7     5\n"
    54   "3 6 8     5\n"
    55   "4 3 9     3\n"
    56   "5 7 10    3\n"
    57   "5 6 11    10\n"
    58   "5 8 12    10\n"
    59   "6 8 13    8\n"
    60   "8 9 14    20\n"
    61   "8 1 15    5\n"
    62   "9 5 16    5\n"
    63   "@attributes\n"
    64   "source 1\n"
    65   "target 8\n";
    66 
    67 void checkPreflowCompile()
    68 {
    69   typedef int VType;
    70   typedef concepts::Digraph Digraph;
    71 
    72   typedef Digraph::Node Node;
    73   typedef Digraph::Arc Arc;
    74   typedef concepts::ReadMap<Arc,VType> CapMap;
    75   typedef concepts::ReadWriteMap<Arc,VType> FlowMap;
    76   typedef concepts::WriteMap<Node,bool> CutMap;
    77 
    78   typedef Elevator<Digraph, Digraph::Node> Elev;
    79   typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;
    80 
    81   Digraph g;
    82   Node n;
    83   Arc e;
    84   CapMap cap;
    85   FlowMap flow;
    86   CutMap cut;
    87   VType v;
    88   bool b;
    89 
    90   typedef Preflow<Digraph, CapMap>
    91             ::SetFlowMap<FlowMap>
    92             ::SetElevator<Elev>
    93             ::SetStandardElevator<LinkedElev>
    94             ::Create PreflowType;
    95   PreflowType preflow_test(g, cap, n, n);
    96   const PreflowType& const_preflow_test = preflow_test;
    97 
    98   const PreflowType::Elevator& elev = const_preflow_test.elevator();
    99   preflow_test.elevator(const_cast<PreflowType::Elevator&>(elev));
   100   PreflowType::Tolerance tol = const_preflow_test.tolerance();
   101   preflow_test.tolerance(tol);
   102 
   103   preflow_test
   104     .capacityMap(cap)
   105     .flowMap(flow)
   106     .source(n)
   107     .target(n);
   108 
   109   preflow_test.init();
   110   preflow_test.init(cap);
   111   preflow_test.startFirstPhase();
   112   preflow_test.startSecondPhase();
   113   preflow_test.run();
   114   preflow_test.runMinCut();
   115 
   116   v = const_preflow_test.flowValue();
   117   v = const_preflow_test.flow(e);
   118   const FlowMap& fm = const_preflow_test.flowMap();
   119   b = const_preflow_test.minCut(n);
   120   const_preflow_test.minCutMap(cut);
   121 
   122   ignore_unused_variable_warning(fm);
   123 }
   124 
   125 int cutValue (const SmartDigraph& g,
   126               const SmartDigraph::NodeMap<bool>& cut,
   127               const SmartDigraph::ArcMap<int>& cap) {
   128 
   129   int c=0;
   130   for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
   131     if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
   132   }
   133   return c;
   134 }
   135 
   136 bool checkFlow(const SmartDigraph& g,
   137                const SmartDigraph::ArcMap<int>& flow,
   138                const SmartDigraph::ArcMap<int>& cap,
   139                SmartDigraph::Node s, SmartDigraph::Node t) {
   140 
   141   for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
   142     if (flow[e] < 0 || flow[e] > cap[e]) return false;
   143   }
   144 
   145   for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
   146     if (n == s || n == t) continue;
   147     int sum = 0;
   148     for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
   149       sum += flow[e];
   150     }
   151     for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
   152       sum -= flow[e];
   153     }
   154     if (sum != 0) return false;
   155   }
   156   return true;
   157 }
   158 
   159 void initFlowTest()
   160 {
   161   DIGRAPH_TYPEDEFS(SmartDigraph);
   162   
   163   SmartDigraph g;
   164   SmartDigraph::ArcMap<int> cap(g),iflow(g);
   165   Node s=g.addNode(); Node t=g.addNode();
   166   Node n1=g.addNode(); Node n2=g.addNode();
   167   Arc a;
   168   a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
   169   a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
   170   a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
   171 
   172   Preflow<SmartDigraph> pre(g,cap,s,t);
   173   pre.init(iflow);
   174   pre.startFirstPhase();
   175   check(pre.flowValue() == 10, "The incorrect max flow value.");
   176   check(pre.minCut(s), "Wrong min cut (Node s).");
   177   check(pre.minCut(n1), "Wrong min cut (Node n1).");
   178   check(!pre.minCut(n2), "Wrong min cut (Node n2).");
   179   check(!pre.minCut(t), "Wrong min cut (Node t).");
   180 }
   181 
   182 
   183 int main() {
   184 
   185   typedef SmartDigraph Digraph;
   186 
   187   typedef Digraph::Node Node;
   188   typedef Digraph::NodeIt NodeIt;
   189   typedef Digraph::ArcIt ArcIt;
   190   typedef Digraph::ArcMap<int> CapMap;
   191   typedef Digraph::ArcMap<int> FlowMap;
   192   typedef Digraph::NodeMap<bool> CutMap;
   193 
   194   typedef Preflow<Digraph, CapMap> PType;
   195 
   196   Digraph g;
   197   Node s, t;
   198   CapMap cap(g);
   199   std::istringstream input(test_lgf);
   200   DigraphReader<Digraph>(g,input).
   201     arcMap("capacity", cap).
   202     node("source",s).
   203     node("target",t).
   204     run();
   205 
   206   PType preflow_test(g, cap, s, t);
   207   preflow_test.run();
   208 
   209   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   210         "The flow is not feasible.");
   211 
   212   CutMap min_cut(g);
   213   preflow_test.minCutMap(min_cut);
   214   int min_cut_value=cutValue(g,min_cut,cap);
   215 
   216   check(preflow_test.flowValue() == min_cut_value,
   217         "The max flow value is not equal to the three min cut values.");
   218 
   219   FlowMap flow(g);
   220   for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
   221 
   222   int flow_value=preflow_test.flowValue();
   223 
   224   for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
   225   preflow_test.init(flow);
   226   preflow_test.startFirstPhase();
   227 
   228   CutMap min_cut1(g);
   229   preflow_test.minCutMap(min_cut1);
   230   min_cut_value=cutValue(g,min_cut1,cap);
   231 
   232   check(preflow_test.flowValue() == min_cut_value &&
   233         min_cut_value == 2*flow_value,
   234         "The max flow value or the min cut value is wrong.");
   235 
   236   preflow_test.startSecondPhase();
   237 
   238   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   239         "The flow is not feasible.");
   240 
   241   CutMap min_cut2(g);
   242   preflow_test.minCutMap(min_cut2);
   243   min_cut_value=cutValue(g,min_cut2,cap);
   244 
   245   check(preflow_test.flowValue() == min_cut_value &&
   246         min_cut_value == 2*flow_value,
   247         "The max flow value or the three min cut values were not doubled");
   248 
   249 
   250   preflow_test.flowMap(flow);
   251 
   252   NodeIt tmp1(g,s);
   253   ++tmp1;
   254   if ( tmp1 != INVALID ) s=tmp1;
   255 
   256   NodeIt tmp2(g,t);
   257   ++tmp2;
   258   if ( tmp2 != INVALID ) t=tmp2;
   259 
   260   preflow_test.source(s);
   261   preflow_test.target(t);
   262 
   263   preflow_test.run();
   264 
   265   CutMap min_cut3(g);
   266   preflow_test.minCutMap(min_cut3);
   267   min_cut_value=cutValue(g,min_cut3,cap);
   268 
   269 
   270   check(preflow_test.flowValue() == min_cut_value,
   271         "The max flow value or the three min cut values are incorrect.");
   272 
   273   initFlowTest();
   274   
   275   return 0;
   276 }