test/preflow_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Sat, 10 Aug 2013 14:27:19 +0200
branch1.2
changeset 992 92d53f86d1a9
parent 972 1fe3b4ad8caa
parent 983 8b2d4e5d96e4
permissions -rw-r--r--
LEMON 1.2.4 released (e13061207f85 tagged as r1.2.4)
     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) 2003-2011
     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   ::lemon::ignore_unused_variable_warning(v,b);
    90 
    91   typedef Preflow<Digraph, CapMap>
    92             ::SetFlowMap<FlowMap>
    93             ::SetElevator<Elev>
    94             ::SetStandardElevator<LinkedElev>
    95             ::Create PreflowType;
    96   PreflowType preflow_test(g, cap, n, n);
    97   const PreflowType& const_preflow_test = preflow_test;
    98 
    99   const PreflowType::Elevator& elev = const_preflow_test.elevator();
   100   preflow_test.elevator(const_cast<PreflowType::Elevator&>(elev));
   101   PreflowType::Tolerance tol = const_preflow_test.tolerance();
   102   preflow_test.tolerance(tol);
   103 
   104   preflow_test
   105     .capacityMap(cap)
   106     .flowMap(flow)
   107     .source(n)
   108     .target(n);
   109 
   110   preflow_test.init();
   111   preflow_test.init(cap);
   112   preflow_test.startFirstPhase();
   113   preflow_test.startSecondPhase();
   114   preflow_test.run();
   115   preflow_test.runMinCut();
   116 
   117   v = const_preflow_test.flowValue();
   118   v = const_preflow_test.flow(e);
   119   const FlowMap& fm = const_preflow_test.flowMap();
   120   b = const_preflow_test.minCut(n);
   121   const_preflow_test.minCutMap(cut);
   122 
   123   ::lemon::ignore_unused_variable_warning(fm);
   124 }
   125 
   126 int cutValue (const SmartDigraph& g,
   127               const SmartDigraph::NodeMap<bool>& cut,
   128               const SmartDigraph::ArcMap<int>& cap) {
   129 
   130   int c=0;
   131   for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
   132     if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
   133   }
   134   return c;
   135 }
   136 
   137 bool checkFlow(const SmartDigraph& g,
   138                const SmartDigraph::ArcMap<int>& flow,
   139                const SmartDigraph::ArcMap<int>& cap,
   140                SmartDigraph::Node s, SmartDigraph::Node t) {
   141 
   142   for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
   143     if (flow[e] < 0 || flow[e] > cap[e]) return false;
   144   }
   145 
   146   for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
   147     if (n == s || n == t) continue;
   148     int sum = 0;
   149     for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
   150       sum += flow[e];
   151     }
   152     for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
   153       sum -= flow[e];
   154     }
   155     if (sum != 0) return false;
   156   }
   157   return true;
   158 }
   159 
   160 void initFlowTest()
   161 {
   162   DIGRAPH_TYPEDEFS(SmartDigraph);
   163 
   164   SmartDigraph g;
   165   SmartDigraph::ArcMap<int> cap(g),iflow(g);
   166   Node s=g.addNode(); Node t=g.addNode();
   167   Node n1=g.addNode(); Node n2=g.addNode();
   168   Arc a;
   169   a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
   170   a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
   171   a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
   172 
   173   Preflow<SmartDigraph> pre(g,cap,s,t);
   174   pre.init(iflow);
   175   pre.startFirstPhase();
   176   check(pre.flowValue() == 10, "The incorrect max flow value.");
   177   check(pre.minCut(s), "Wrong min cut (Node s).");
   178   check(pre.minCut(n1), "Wrong min cut (Node n1).");
   179   check(!pre.minCut(n2), "Wrong min cut (Node n2).");
   180   check(!pre.minCut(t), "Wrong min cut (Node t).");
   181 }
   182 
   183 
   184 int main() {
   185 
   186   typedef SmartDigraph Digraph;
   187 
   188   typedef Digraph::Node Node;
   189   typedef Digraph::NodeIt NodeIt;
   190   typedef Digraph::ArcIt ArcIt;
   191   typedef Digraph::ArcMap<int> CapMap;
   192   typedef Digraph::ArcMap<int> FlowMap;
   193   typedef Digraph::NodeMap<bool> CutMap;
   194 
   195   typedef Preflow<Digraph, CapMap> PType;
   196 
   197   Digraph g;
   198   Node s, t;
   199   CapMap cap(g);
   200   std::istringstream input(test_lgf);
   201   DigraphReader<Digraph>(g,input).
   202     arcMap("capacity", cap).
   203     node("source",s).
   204     node("target",t).
   205     run();
   206 
   207   PType preflow_test(g, cap, s, t);
   208   preflow_test.run();
   209 
   210   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   211         "The flow is not feasible.");
   212 
   213   CutMap min_cut(g);
   214   preflow_test.minCutMap(min_cut);
   215   int min_cut_value=cutValue(g,min_cut,cap);
   216 
   217   check(preflow_test.flowValue() == min_cut_value,
   218         "The max flow value is not equal to the three min cut values.");
   219 
   220   FlowMap flow(g);
   221   for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
   222 
   223   int flow_value=preflow_test.flowValue();
   224 
   225   for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
   226   preflow_test.init(flow);
   227   preflow_test.startFirstPhase();
   228 
   229   CutMap min_cut1(g);
   230   preflow_test.minCutMap(min_cut1);
   231   min_cut_value=cutValue(g,min_cut1,cap);
   232 
   233   check(preflow_test.flowValue() == min_cut_value &&
   234         min_cut_value == 2*flow_value,
   235         "The max flow value or the min cut value is wrong.");
   236 
   237   preflow_test.startSecondPhase();
   238 
   239   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   240         "The flow is not feasible.");
   241 
   242   CutMap min_cut2(g);
   243   preflow_test.minCutMap(min_cut2);
   244   min_cut_value=cutValue(g,min_cut2,cap);
   245 
   246   check(preflow_test.flowValue() == min_cut_value &&
   247         min_cut_value == 2*flow_value,
   248         "The max flow value or the three min cut values were not doubled");
   249 
   250 
   251   preflow_test.flowMap(flow);
   252 
   253   NodeIt tmp1(g,s);
   254   ++tmp1;
   255   if ( tmp1 != INVALID ) s=tmp1;
   256 
   257   NodeIt tmp2(g,t);
   258   ++tmp2;
   259   if ( tmp2 != INVALID ) t=tmp2;
   260 
   261   preflow_test.source(s);
   262   preflow_test.target(t);
   263 
   264   preflow_test.run();
   265 
   266   CutMap min_cut3(g);
   267   preflow_test.minCutMap(min_cut3);
   268   min_cut_value=cutValue(g,min_cut3,cap);
   269 
   270 
   271   check(preflow_test.flowValue() == min_cut_value,
   272         "The max flow value or the three min cut values are incorrect.");
   273 
   274   initFlowTest();
   275 
   276   return 0;
   277 }