test/bellman_ford_test.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Thu, 04 Mar 2010 10:03:14 +0100
changeset 862 b6f76c95992e
parent 791 4e3484a2e90c
child 877 141f9c0db4a3
child 878 d6052a9c4e8d
permissions -rw-r--r--
Clarify type names in NetworkSimplex (#353)

This patch clarifies the misleading effects of the renamings
in [f3bc4e9b5f3a].
     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       ::SetOperationTraits<BellmanFordToleranceOperationTraits<Value, 0> >
   108       ::Create bf_test(gr,length);
   109 
   110     LengthMap length_map;
   111     concepts::ReadWriteMap<Node,Arc> pred_map;
   112     concepts::ReadWriteMap<Node,Value> dist_map;
   113     
   114     bf_test
   115       .lengthMap(length_map)
   116       .predMap(pred_map)
   117       .distMap(dist_map);
   118 
   119     bf_test.run(s);
   120     bf_test.run(s,k);
   121 
   122     bf_test.init();
   123     bf_test.addSource(s);
   124     bf_test.addSource(s, 1);
   125     b = bf_test.processNextRound();
   126     b = bf_test.processNextWeakRound();
   127 
   128     bf_test.start();
   129     bf_test.checkedStart();
   130     bf_test.limitedStart(k);
   131 
   132     l  = bf_test.dist(t);
   133     e  = bf_test.predArc(t);
   134     s  = bf_test.predNode(t);
   135     b  = bf_test.reached(t);
   136     pp = bf_test.path(t);
   137     pp = bf_test.negativeCycle();
   138   }
   139 }
   140 
   141 void checkBellmanFordFunctionCompile()
   142 {
   143   typedef int Value;
   144   typedef concepts::Digraph Digraph;
   145   typedef Digraph::Arc Arc;
   146   typedef Digraph::Node Node;
   147   typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
   148 
   149   Digraph g;
   150   bool b;
   151   bellmanFord(g,LengthMap()).run(Node());
   152   b = bellmanFord(g,LengthMap()).run(Node(),Node());
   153   bellmanFord(g,LengthMap())
   154     .predMap(concepts::ReadWriteMap<Node,Arc>())
   155     .distMap(concepts::ReadWriteMap<Node,Value>())
   156     .run(Node());
   157   b=bellmanFord(g,LengthMap())
   158     .predMap(concepts::ReadWriteMap<Node,Arc>())
   159     .distMap(concepts::ReadWriteMap<Node,Value>())
   160     .path(concepts::Path<Digraph>())
   161     .dist(Value())
   162     .run(Node(),Node());
   163 }
   164 
   165 
   166 template <typename Digraph, typename Value>
   167 void checkBellmanFord() {
   168   TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
   169   typedef typename Digraph::template ArcMap<Value> LengthMap;
   170 
   171   Digraph gr;
   172   Node s, t;
   173   LengthMap length(gr);
   174 
   175   std::istringstream input(test_lgf);
   176   digraphReader(gr, input).
   177     arcMap("length", length).
   178     node("source", s).
   179     node("target", t).
   180     run();
   181 
   182   BellmanFord<Digraph, LengthMap>
   183     bf(gr, length);
   184   bf.run(s);
   185   Path<Digraph> p = bf.path(t);
   186 
   187   check(bf.reached(t) && bf.dist(t) == -1, "Bellman-Ford found a wrong path.");
   188   check(p.length() == 3, "path() found a wrong path.");
   189   check(checkPath(gr, p), "path() found a wrong path.");
   190   check(pathSource(gr, p) == s, "path() found a wrong path.");
   191   check(pathTarget(gr, p) == t, "path() found a wrong path.");
   192   
   193   ListPath<Digraph> path;
   194   Value dist;
   195   bool reached = bellmanFord(gr,length).path(path).dist(dist).run(s,t);
   196 
   197   check(reached && dist == -1, "Bellman-Ford found a wrong path.");
   198   check(path.length() == 3, "path() found a wrong path.");
   199   check(checkPath(gr, path), "path() found a wrong path.");
   200   check(pathSource(gr, path) == s, "path() found a wrong path.");
   201   check(pathTarget(gr, path) == t, "path() found a wrong path.");
   202 
   203   for(ArcIt e(gr); e!=INVALID; ++e) {
   204     Node u=gr.source(e);
   205     Node v=gr.target(e);
   206     check(!bf.reached(u) || (bf.dist(v) - bf.dist(u) <= length[e]),
   207           "Wrong output. dist(target)-dist(source)-arc_length=" <<
   208           bf.dist(v) - bf.dist(u) - length[e]);
   209   }
   210 
   211   for(NodeIt v(gr); v!=INVALID; ++v) {
   212     if (bf.reached(v)) {
   213       check(v==s || bf.predArc(v)!=INVALID, "Wrong tree.");
   214       if (bf.predArc(v)!=INVALID ) {
   215         Arc e=bf.predArc(v);
   216         Node u=gr.source(e);
   217         check(u==bf.predNode(v),"Wrong tree.");
   218         check(bf.dist(v) - bf.dist(u) == length[e],
   219               "Wrong distance! Difference: " <<
   220               bf.dist(v) - bf.dist(u) - length[e]);
   221       }
   222     }
   223   }
   224 }
   225 
   226 void checkBellmanFordNegativeCycle() {
   227   DIGRAPH_TYPEDEFS(SmartDigraph);
   228 
   229   SmartDigraph gr;
   230   IntArcMap length(gr);
   231   
   232   Node n1 = gr.addNode();
   233   Node n2 = gr.addNode();
   234   Node n3 = gr.addNode();
   235   Node n4 = gr.addNode();
   236   
   237   Arc a1 = gr.addArc(n1, n2);
   238   Arc a2 = gr.addArc(n2, n2);
   239   
   240   length[a1] = 2;
   241   length[a2] = -1;
   242   
   243   {
   244     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   245     bf.run(n1);
   246     StaticPath<SmartDigraph> p = bf.negativeCycle();
   247     check(p.length() == 1 && p.front() == p.back() && p.front() == a2,
   248           "Wrong negative cycle.");
   249   }
   250  
   251   length[a2] = 0;
   252   
   253   {
   254     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   255     bf.run(n1);
   256     check(bf.negativeCycle().empty(),
   257           "Negative cycle should not be found.");
   258   }
   259   
   260   length[gr.addArc(n1, n3)] = 5;
   261   length[gr.addArc(n4, n3)] = 1;
   262   length[gr.addArc(n2, n4)] = 2;
   263   length[gr.addArc(n3, n2)] = -4;
   264   
   265   {
   266     BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
   267     bf.init();
   268     bf.addSource(n1);
   269     for (int i = 0; i < 4; ++i) {
   270       check(bf.negativeCycle().empty(),
   271             "Negative cycle should not be found.");
   272       bf.processNextRound();
   273     }
   274     StaticPath<SmartDigraph> p = bf.negativeCycle();
   275     check(p.length() == 3, "Wrong negative cycle.");
   276     check(length[p.nth(0)] + length[p.nth(1)] + length[p.nth(2)] == -1,
   277           "Wrong negative cycle.");
   278   }
   279 }
   280 
   281 int main() {
   282   checkBellmanFord<ListDigraph, int>();
   283   checkBellmanFord<SmartDigraph, double>();
   284   checkBellmanFordNegativeCycle();
   285   return 0;
   286 }