test/preflow_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Fri, 20 Feb 2009 21:37:19 +0000
changeset 517 2b6d5d22bb23
parent 423 ff48c2738fb2
child 585 65fbcf2f978a
permissions -rw-r--r--
Merge
     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 
    88   Preflow<Digraph, CapMap>
    89     ::SetFlowMap<FlowMap>
    90     ::SetElevator<Elev>
    91     ::SetStandardElevator<LinkedElev>
    92     ::Create preflow_test(g,cap,n,n);
    93 
    94   preflow_test.capacityMap(cap);
    95   flow = preflow_test.flowMap();
    96   preflow_test.flowMap(flow);
    97   preflow_test.source(n);
    98   preflow_test.target(n);
    99 
   100   preflow_test.init();
   101   preflow_test.init(cap);
   102   preflow_test.startFirstPhase();
   103   preflow_test.startSecondPhase();
   104   preflow_test.run();
   105   preflow_test.runMinCut();
   106 
   107   preflow_test.flowValue();
   108   preflow_test.minCut(n);
   109   preflow_test.minCutMap(cut);
   110   preflow_test.flow(e);
   111 
   112 }
   113 
   114 int cutValue (const SmartDigraph& g,
   115               const SmartDigraph::NodeMap<bool>& cut,
   116               const SmartDigraph::ArcMap<int>& cap) {
   117 
   118   int c=0;
   119   for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
   120     if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
   121   }
   122   return c;
   123 }
   124 
   125 bool checkFlow(const SmartDigraph& g,
   126                const SmartDigraph::ArcMap<int>& flow,
   127                const SmartDigraph::ArcMap<int>& cap,
   128                SmartDigraph::Node s, SmartDigraph::Node t) {
   129 
   130   for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
   131     if (flow[e] < 0 || flow[e] > cap[e]) return false;
   132   }
   133 
   134   for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
   135     if (n == s || n == t) continue;
   136     int sum = 0;
   137     for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
   138       sum += flow[e];
   139     }
   140     for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
   141       sum -= flow[e];
   142     }
   143     if (sum != 0) return false;
   144   }
   145   return true;
   146 }
   147 
   148 int main() {
   149 
   150   typedef SmartDigraph Digraph;
   151 
   152   typedef Digraph::Node Node;
   153   typedef Digraph::NodeIt NodeIt;
   154   typedef Digraph::ArcIt ArcIt;
   155   typedef Digraph::ArcMap<int> CapMap;
   156   typedef Digraph::ArcMap<int> FlowMap;
   157   typedef Digraph::NodeMap<bool> CutMap;
   158 
   159   typedef Preflow<Digraph, CapMap> PType;
   160 
   161   Digraph g;
   162   Node s, t;
   163   CapMap cap(g);
   164   std::istringstream input(test_lgf);
   165   DigraphReader<Digraph>(g,input).
   166     arcMap("capacity", cap).
   167     node("source",s).
   168     node("target",t).
   169     run();
   170 
   171   PType preflow_test(g, cap, s, t);
   172   preflow_test.run();
   173 
   174   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   175         "The flow is not feasible.");
   176 
   177   CutMap min_cut(g);
   178   preflow_test.minCutMap(min_cut);
   179   int min_cut_value=cutValue(g,min_cut,cap);
   180 
   181   check(preflow_test.flowValue() == min_cut_value,
   182         "The max flow value is not equal to the three min cut values.");
   183 
   184   FlowMap flow(g);
   185   for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
   186 
   187   int flow_value=preflow_test.flowValue();
   188 
   189   for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
   190   preflow_test.init(flow);
   191   preflow_test.startFirstPhase();
   192 
   193   CutMap min_cut1(g);
   194   preflow_test.minCutMap(min_cut1);
   195   min_cut_value=cutValue(g,min_cut1,cap);
   196 
   197   check(preflow_test.flowValue() == min_cut_value &&
   198         min_cut_value == 2*flow_value,
   199         "The max flow value or the min cut value is wrong.");
   200 
   201   preflow_test.startSecondPhase();
   202 
   203   check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
   204         "The flow is not feasible.");
   205 
   206   CutMap min_cut2(g);
   207   preflow_test.minCutMap(min_cut2);
   208   min_cut_value=cutValue(g,min_cut2,cap);
   209 
   210   check(preflow_test.flowValue() == min_cut_value &&
   211         min_cut_value == 2*flow_value,
   212         "The max flow value or the three min cut values were not doubled");
   213 
   214 
   215   preflow_test.flowMap(flow);
   216 
   217   NodeIt tmp1(g,s);
   218   ++tmp1;
   219   if ( tmp1 != INVALID ) s=tmp1;
   220 
   221   NodeIt tmp2(g,t);
   222   ++tmp2;
   223   if ( tmp2 != INVALID ) t=tmp2;
   224 
   225   preflow_test.source(s);
   226   preflow_test.target(t);
   227 
   228   preflow_test.run();
   229 
   230   CutMap min_cut3(g);
   231   preflow_test.minCutMap(min_cut3);
   232   min_cut_value=cutValue(g,min_cut3,cap);
   233 
   234 
   235   check(preflow_test.flowValue() == min_cut_value,
   236         "The max flow value or the three min cut values are incorrect.");
   237 
   238   return 0;
   239 }