test/preflow_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Tue, 12 May 2009 11:49:13 +0100
changeset 665 e652b6f9a29f
parent 440 88ed40ad0d4f
child 689 86c49553fea5
child 923 30d5f950aa5f
permissions -rw-r--r--
Update NEWS file
     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) 2003-2009
     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   preflow_test
    99     .capacityMap(cap)
   100     .flowMap(flow)
   101     .source(n)
   102     .target(n);
   103 
   104   preflow_test.init();
   105   preflow_test.init(cap);
   106   preflow_test.startFirstPhase();
   107   preflow_test.startSecondPhase();
   108   preflow_test.run();
   109   preflow_test.runMinCut();
   110 
   111   v = const_preflow_test.flowValue();
   112   v = const_preflow_test.flow(e);
   113   const FlowMap& fm = const_preflow_test.flowMap();
   114   b = const_preflow_test.minCut(n);
   115   const_preflow_test.minCutMap(cut);
   116   
   117   ignore_unused_variable_warning(fm);
   118 }
   119 
   120 int cutValue (const SmartDigraph& g,
   121               const SmartDigraph::NodeMap<bool>& cut,
   122               const SmartDigraph::ArcMap<int>& cap) {
   123 
   124   int c=0;
   125   for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
   126     if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
   127   }
   128   return c;
   129 }
   130 
   131 bool checkFlow(const SmartDigraph& g,
   132                const SmartDigraph::ArcMap<int>& flow,
   133                const SmartDigraph::ArcMap<int>& cap,
   134                SmartDigraph::Node s, SmartDigraph::Node t) {
   135 
   136   for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
   137     if (flow[e] < 0 || flow[e] > cap[e]) return false;
   138   }
   139 
   140   for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
   141     if (n == s || n == t) continue;
   142     int sum = 0;
   143     for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
   144       sum += flow[e];
   145     }
   146     for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
   147       sum -= flow[e];
   148     }
   149     if (sum != 0) return false;
   150   }
   151   return true;
   152 }
   153 
   154 int main() {
   155 
   156   typedef SmartDigraph Digraph;
   157 
   158   typedef Digraph::Node Node;
   159   typedef Digraph::NodeIt NodeIt;
   160   typedef Digraph::ArcIt ArcIt;
   161   typedef Digraph::ArcMap<int> CapMap;
   162   typedef Digraph::ArcMap<int> FlowMap;
   163   typedef Digraph::NodeMap<bool> CutMap;
   164 
   165   typedef Preflow<Digraph, CapMap> PType;
   166 
   167   Digraph g;
   168   Node s, t;
   169   CapMap cap(g);
   170   std::istringstream input(test_lgf);
   171   DigraphReader<Digraph>(g,input).
   172     arcMap("capacity", cap).
   173     node("source",s).
   174     node("target",t).
   175     run();
   176 
   177   PType preflow_test(g, cap, s, t);
   178   preflow_test.run();
   179 
   180   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   181         "The flow is not feasible.");
   182 
   183   CutMap min_cut(g);
   184   preflow_test.minCutMap(min_cut);
   185   int min_cut_value=cutValue(g,min_cut,cap);
   186 
   187   check(preflow_test.flowValue() == min_cut_value,
   188         "The max flow value is not equal to the three min cut values.");
   189 
   190   FlowMap flow(g);
   191   for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
   192 
   193   int flow_value=preflow_test.flowValue();
   194 
   195   for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
   196   preflow_test.init(flow);
   197   preflow_test.startFirstPhase();
   198 
   199   CutMap min_cut1(g);
   200   preflow_test.minCutMap(min_cut1);
   201   min_cut_value=cutValue(g,min_cut1,cap);
   202 
   203   check(preflow_test.flowValue() == min_cut_value &&
   204         min_cut_value == 2*flow_value,
   205         "The max flow value or the min cut value is wrong.");
   206 
   207   preflow_test.startSecondPhase();
   208 
   209   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   210         "The flow is not feasible.");
   211 
   212   CutMap min_cut2(g);
   213   preflow_test.minCutMap(min_cut2);
   214   min_cut_value=cutValue(g,min_cut2,cap);
   215 
   216   check(preflow_test.flowValue() == min_cut_value &&
   217         min_cut_value == 2*flow_value,
   218         "The max flow value or the three min cut values were not doubled");
   219 
   220 
   221   preflow_test.flowMap(flow);
   222 
   223   NodeIt tmp1(g,s);
   224   ++tmp1;
   225   if ( tmp1 != INVALID ) s=tmp1;
   226 
   227   NodeIt tmp2(g,t);
   228   ++tmp2;
   229   if ( tmp2 != INVALID ) t=tmp2;
   230 
   231   preflow_test.source(s);
   232   preflow_test.target(t);
   233 
   234   preflow_test.run();
   235 
   236   CutMap min_cut3(g);
   237   preflow_test.minCutMap(min_cut3);
   238   min_cut_value=cutValue(g,min_cut3,cap);
   239 
   240 
   241   check(preflow_test.flowValue() == min_cut_value,
   242         "The max flow value or the three min cut values are incorrect.");
   243 
   244   return 0;
   245 }