test/bellman_ford_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Wed, 18 Nov 2009 14:22:52 +0100
changeset 838 4e3484a2e90c
parent 828 6f10c6ec5a21
parent 837 1870cfd14fb6
child 917 a6eb9698c321
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 <lemon/concepts/digraph.h>
    20 #include <lemon/smart_graph.h>
    21 #include <lemon/list_graph.h>
    22 #include <lemon/lgf_reader.h>
    23 #include <lemon/bellman_ford.h>
    24 #include <lemon/path.h>
    25 
    26 #include "graph_test.h"
    27 #include "test_tools.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   "@arcs\n"
    40   "    length\n"
    41   "0 1 3\n"
    42   "1 2 -3\n"
    43   "1 2 -5\n"
    44   "1 3 -2\n"
    45   "0 2 -1\n"
    46   "1 2 -4\n"
    47   "0 3 2\n"
    48   "4 2 -5\n"
    49   "2 3 1\n"
    50   "@attributes\n"
    51   "source 0\n"
    52   "target 3\n";
    53 
    54 
    55 void checkBellmanFordCompile()
    56 {
    57   typedef int Value;
    58   typedef concepts::Digraph Digraph;
    59   typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
    60   typedef BellmanFord<Digraph, LengthMap> BF;
    61   typedef Digraph::Node Node;
    62   typedef Digraph::Arc Arc;
    63 
    64   Digraph gr;
    65   Node s, t, n;
    66   Arc e;
    67   Value l;
    68   int k=3;
    69   bool b;
    70   BF::DistMap d(gr);
    71   BF::PredMap p(gr);
    72   LengthMap length;
    73   concepts::Path<Digraph> pp;
    74 
    75   {
    76     BF bf_test(gr,length);
    77     const BF& const_bf_test = bf_test;
    78 
    79     bf_test.run(s);
    80     bf_test.run(s,k);
    81 
    82     bf_test.init();
    83     bf_test.addSource(s);
    84     bf_test.addSource(s, 1);
    85     b = bf_test.processNextRound();
    86     b = bf_test.processNextWeakRound();
    87 
    88     bf_test.start();
    89     bf_test.checkedStart();
    90     bf_test.limitedStart(k);
    91 
    92     l  = const_bf_test.dist(t);
    93     e  = const_bf_test.predArc(t);
    94     s  = const_bf_test.predNode(t);
    95     b  = const_bf_test.reached(t);
    96     d  = const_bf_test.distMap();
    97     p  = const_bf_test.predMap();
    98     pp = const_bf_test.path(t);
    99     pp = const_bf_test.negativeCycle();
   100     
   101     for (BF::ActiveIt it(const_bf_test); it != INVALID; ++it) {}
   102   }
   103   {
   104     BF::SetPredMap<concepts::ReadWriteMap<Node,Arc> >
   105       ::SetDistMap<concepts::ReadWriteMap<Node,Value> >
   106       ::SetOperationTraits<BellmanFordDefaultOperationTraits<Value> >
   107       ::Create bf_test(gr,length);
   108 
   109     LengthMap length_map;
   110     concepts::ReadWriteMap<Node,Arc> pred_map;
   111     concepts::ReadWriteMap<Node,Value> dist_map;
   112     
   113     bf_test
   114       .lengthMap(length_map)
   115       .predMap(pred_map)
   116       .distMap(dist_map);
   117 
   118     bf_test.run(s);
   119     bf_test.run(s,k);
   120 
   121     bf_test.init();
   122     bf_test.addSource(s);
   123     bf_test.addSource(s, 1);
   124     b = bf_test.processNextRound();
   125     b = bf_test.processNextWeakRound();
   126 
   127     bf_test.start();
   128     bf_test.checkedStart();
   129     bf_test.limitedStart(k);
   130 
   131     l  = bf_test.dist(t);
   132     e  = bf_test.predArc(t);
   133     s  = bf_test.predNode(t);
   134     b  = bf_test.reached(t);
   135     pp = bf_test.path(t);
   136     pp = bf_test.negativeCycle();
   137   }
   138 }
   139 
   140 void checkBellmanFordFunctionCompile()
   141 {
   142   typedef int Value;
   143   typedef concepts::Digraph Digraph;
   144   typedef Digraph::Arc Arc;
   145   typedef Digraph::Node Node;
   146   typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
   147 
   148   Digraph g;
   149   bool b;
   150   bellmanFord(g,LengthMap()).run(Node());
   151   b = bellmanFord(g,LengthMap()).run(Node(),Node());
   152   bellmanFord(g,LengthMap())
   153     .predMap(concepts::ReadWriteMap<Node,Arc>())
   154     .distMap(concepts::ReadWriteMap<Node,Value>())
   155     .run(Node());
   156   b=bellmanFord(g,LengthMap())
   157     .predMap(concepts::ReadWriteMap<Node,Arc>())
   158     .distMap(concepts::ReadWriteMap<Node,Value>())
   159     .path(concepts::Path<Digraph>())
   160     .dist(Value())
   161     .run(Node(),Node());
   162 }
   163 
   164 
   165 template <typename Digraph, typename Value>
   166 void checkBellmanFord() {
   167   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
   168   typedef typename Digraph::template ArcMap<Value> LengthMap;
   169 
   170   Digraph gr;
   171   Node s, t;
   172   LengthMap length(gr);
   173 
   174   std::istringstream input(test_lgf);
   175   digraphReader(gr, input).
   176     arcMap("length", length).
   177     node("source", s).
   178     node("target", t).
   179     run();
   180 
   181   BellmanFord<Digraph, LengthMap>
   182     bf(gr, length);
   183   bf.run(s);
   184   Path<Digraph> p = bf.path(t);
   185 
   186   check(bf.reached(t) && bf.dist(t) == -1, "Bellman-Ford found a wrong path.");
   187   check(p.length() == 3, "path() found a wrong path.");
   188   check(checkPath(gr, p), "path() found a wrong path.");
   189   check(pathSource(gr, p) == s, "path() found a wrong path.");
   190   check(pathTarget(gr, p) == t, "path() found a wrong path.");
   191   
   192   ListPath<Digraph> path;
   193   Value dist;
   194   bool reached = bellmanFord(gr,length).path(path).dist(dist).run(s,t);
   195 
   196   check(reached && dist == -1, "Bellman-Ford found a wrong path.");
   197   check(path.length() == 3, "path() found a wrong path.");
   198   check(checkPath(gr, path), "path() found a wrong path.");
   199   check(pathSource(gr, path) == s, "path() found a wrong path.");
   200   check(pathTarget(gr, path) == t, "path() found a wrong path.");
   201 
   202   for(ArcIt e(gr); e!=INVALID; ++e) {
   203     Node u=gr.source(e);
   204     Node v=gr.target(e);
   205     check(!bf.reached(u) || (bf.dist(v) - bf.dist(u) <= length[e]),
   206           "Wrong output. dist(target)-dist(source)-arc_length=" <<
   207           bf.dist(v) - bf.dist(u) - length[e]);
   208   }
   209 
   210   for(NodeIt v(gr); v!=INVALID; ++v) {
   211     if (bf.reached(v)) {
   212       check(v==s || bf.predArc(v)!=INVALID, "Wrong tree.");
   213       if (bf.predArc(v)!=INVALID ) {
   214         Arc e=bf.predArc(v);
   215         Node u=gr.source(e);
   216         check(u==bf.predNode(v),"Wrong tree.");
   217         check(bf.dist(v) - bf.dist(u) == length[e],
   218               "Wrong distance! Difference: " <<
   219               bf.dist(v) - bf.dist(u) - length[e]);
   220       }
   221     }
   222   }
   223 }
   224 
   225 void checkBellmanFordNegativeCycle() {
   226   DIGRAPH_TYPEDEFS(SmartDigraph);
   227 
   228   SmartDigraph gr;
   229   IntArcMap length(gr);
   230   
   231   Node n1 = gr.addNode();
   232   Node n2 = gr.addNode();
   233   Node n3 = gr.addNode();
   234   Node n4 = gr.addNode();
   235   
   236   Arc a1 = gr.addArc(n1, n2);
   237   Arc a2 = gr.addArc(n2, n2);
   238   
   239   length[a1] = 2;
   240   length[a2] = -1;
   241   
   242   {
   243     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   244     bf.run(n1);
   245     StaticPath<SmartDigraph> p = bf.negativeCycle();
   246     check(p.length() == 1 && p.front() == p.back() && p.front() == a2,
   247           "Wrong negative cycle.");
   248   }
   249  
   250   length[a2] = 0;
   251   
   252   {
   253     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   254     bf.run(n1);
   255     check(bf.negativeCycle().empty(),
   256           "Negative cycle should not be found.");
   257   }
   258   
   259   length[gr.addArc(n1, n3)] = 5;
   260   length[gr.addArc(n4, n3)] = 1;
   261   length[gr.addArc(n2, n4)] = 2;
   262   length[gr.addArc(n3, n2)] = -4;
   263   
   264   {
   265     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   266     bf.init();
   267     bf.addSource(n1);
   268     for (int i = 0; i < 4; ++i) {
   269       check(bf.negativeCycle().empty(),
   270             "Negative cycle should not be found.");
   271       bf.processNextRound();
   272     }
   273     StaticPath<SmartDigraph> p = bf.negativeCycle();
   274     check(p.length() == 3, "Wrong negative cycle.");
   275     check(length[p.nth(0)] + length[p.nth(1)] + length[p.nth(2)] == -1,
   276           "Wrong negative cycle.");
   277   }
   278 }
   279 
   280 int main() {
   281   checkBellmanFord<ListDigraph, int>();
   282   checkBellmanFord<SmartDigraph, double>();
   283   checkBellmanFordNegativeCycle();
   284   return 0;
   285 }