test/bellman_ford_test.cc
author Alpar Juttner <alpar@cs.elte.hu>
Thu, 13 Sep 2012 12:02:27 +0200
changeset 1160 00f8d9f9920d
parent 960 b89e46862dc2
child 1174 a26b90a17c81
permissions -rw-r--r--
Further clang compilation fixes (#449)
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library.
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 *
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 * Copyright (C) 2003-2010
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#include <lemon/concepts/digraph.h>
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#include <lemon/smart_graph.h>
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#include <lemon/list_graph.h>
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#include <lemon/lgf_reader.h>
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#include <lemon/bellman_ford.h>
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#include <lemon/path.h>
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#include "graph_test.h"
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#include "test_tools.h"
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using namespace lemon;
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char test_lgf[] =
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  "@nodes\n"
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  "label\n"
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  "0\n"
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  "1\n"
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  "2\n"
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  "3\n"
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  "4\n"
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  "@arcs\n"
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  "    length\n"
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  "0 1 3\n"
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  "1 2 -3\n"
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  "1 2 -5\n"
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  "1 3 -2\n"
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  "0 2 -1\n"
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  "1 2 -4\n"
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  "0 3 2\n"
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  "4 2 -5\n"
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  "2 3 1\n"
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  "@attributes\n"
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  "source 0\n"
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  "target 3\n";
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void checkBellmanFordCompile()
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{
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  typedef int Value;
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  typedef concepts::Digraph Digraph;
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  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
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  typedef BellmanFord<Digraph, LengthMap> BF;
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  typedef Digraph::Node Node;
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  typedef Digraph::Arc Arc;
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  Digraph gr;
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  Node s, t, n;
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  Arc e;
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  Value l;
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  int k=3;
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  bool b;
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  BF::DistMap d(gr);
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  BF::PredMap p(gr);
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  LengthMap length;
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  concepts::Path<Digraph> pp;
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  {
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    BF bf_test(gr,length);
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    const BF& const_bf_test = bf_test;
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    bf_test.run(s);
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    bf_test.run(s,k);
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    bf_test.init();
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    bf_test.addSource(s);
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    bf_test.addSource(s, 1);
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    b = bf_test.processNextRound();
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    b = bf_test.processNextWeakRound();
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    bf_test.start();
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    bf_test.checkedStart();
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    bf_test.limitedStart(k);
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    l  = const_bf_test.dist(t);
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    e  = const_bf_test.predArc(t);
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    s  = const_bf_test.predNode(t);
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    b  = const_bf_test.reached(t);
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    d  = const_bf_test.distMap();
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    p  = const_bf_test.predMap();
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    pp = const_bf_test.path(t);
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    pp = const_bf_test.negativeCycle();
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    for (BF::ActiveIt it(const_bf_test); it != INVALID; ++it) {}
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  }
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  {
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    BF::SetPredMap<concepts::ReadWriteMap<Node,Arc> >
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      ::SetDistMap<concepts::ReadWriteMap<Node,Value> >
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      ::SetOperationTraits<BellmanFordDefaultOperationTraits<Value> >
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      ::Create bf_test(gr,length);
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    LengthMap length_map;
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    concepts::ReadWriteMap<Node,Arc> pred_map;
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    concepts::ReadWriteMap<Node,Value> dist_map;
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    bf_test
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      .lengthMap(length_map)
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      .predMap(pred_map)
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      .distMap(dist_map);
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    bf_test.run(s);
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    bf_test.run(s,k);
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    bf_test.init();
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    bf_test.addSource(s);
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    bf_test.addSource(s, 1);
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    b = bf_test.processNextRound();
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    b = bf_test.processNextWeakRound();
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    bf_test.start();
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    bf_test.checkedStart();
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    bf_test.limitedStart(k);
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    l  = bf_test.dist(t);
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    e  = bf_test.predArc(t);
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    s  = bf_test.predNode(t);
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    b  = bf_test.reached(t);
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    pp = bf_test.path(t);
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    pp = bf_test.negativeCycle();
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  }
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}
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void checkBellmanFordFunctionCompile()
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{
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  typedef int Value;
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  typedef concepts::Digraph Digraph;
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  typedef Digraph::Arc Arc;
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  typedef Digraph::Node Node;
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  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
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  Digraph g;
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  bool b;
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  bellmanFord(g,LengthMap()).run(Node());
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  b = bellmanFord(g,LengthMap()).run(Node(),Node());
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  bellmanFord(g,LengthMap())
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    .predMap(concepts::ReadWriteMap<Node,Arc>())
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    .distMap(concepts::ReadWriteMap<Node,Value>())
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    .run(Node());
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  b=bellmanFord(g,LengthMap())
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    .predMap(concepts::ReadWriteMap<Node,Arc>())
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    .distMap(concepts::ReadWriteMap<Node,Value>())
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    .path(concepts::Path<Digraph>())
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    .dist(Value())
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    .run(Node(),Node());
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}
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template <typename Digraph, typename Value>
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void checkBellmanFord() {
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  TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
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  typedef typename Digraph::template ArcMap<Value> LengthMap;
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  Digraph gr;
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  Node s, t;
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  LengthMap length(gr);
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  std::istringstream input(test_lgf);
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  digraphReader(gr, input).
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    arcMap("length", length).
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    node("source", s).
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    node("target", t).
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    run();
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  BellmanFord<Digraph, LengthMap>
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    bf(gr, length);
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  bf.run(s);
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  Path<Digraph> p = bf.path(t);
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  check(bf.reached(t) && bf.dist(t) == -1, "Bellman-Ford found a wrong path.");
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  check(p.length() == 3, "path() found a wrong path.");
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  check(checkPath(gr, p), "path() found a wrong path.");
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  check(pathSource(gr, p) == s, "path() found a wrong path.");
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  check(pathTarget(gr, p) == t, "path() found a wrong path.");
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  ListPath<Digraph> path;
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  Value dist = 0;
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  bool reached = bellmanFord(gr,length).path(path).dist(dist).run(s,t);
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  check(reached && dist == -1, "Bellman-Ford found a wrong path.");
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  check(path.length() == 3, "path() found a wrong path.");
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  check(checkPath(gr, path), "path() found a wrong path.");
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  check(pathSource(gr, path) == s, "path() found a wrong path.");
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  check(pathTarget(gr, path) == t, "path() found a wrong path.");
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  for(ArcIt e(gr); e!=INVALID; ++e) {
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    Node u=gr.source(e);
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    Node v=gr.target(e);
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    check(!bf.reached(u) || (bf.dist(v) - bf.dist(u) <= length[e]),
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          "Wrong output. dist(target)-dist(source)-arc_length=" <<
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          bf.dist(v) - bf.dist(u) - length[e]);
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  }
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  for(NodeIt v(gr); v!=INVALID; ++v) {
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    if (bf.reached(v)) {
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      check(v==s || bf.predArc(v)!=INVALID, "Wrong tree.");
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      if (bf.predArc(v)!=INVALID ) {
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        Arc e=bf.predArc(v);
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        Node u=gr.source(e);
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        check(u==bf.predNode(v),"Wrong tree.");
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        check(bf.dist(v) - bf.dist(u) == length[e],
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              "Wrong distance! Difference: " <<
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              bf.dist(v) - bf.dist(u) - length[e]);
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      }
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    }
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  }
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}
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void checkBellmanFordNegativeCycle() {
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  DIGRAPH_TYPEDEFS(SmartDigraph);
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  SmartDigraph gr;
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  IntArcMap length(gr);
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  Node n1 = gr.addNode();
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  Node n2 = gr.addNode();
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  Node n3 = gr.addNode();
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  Node n4 = gr.addNode();
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  Arc a1 = gr.addArc(n1, n2);
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  Arc a2 = gr.addArc(n2, n2);
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  length[a1] = 2;
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  length[a2] = -1;
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  {
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    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
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    bf.run(n1);
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    StaticPath<SmartDigraph> p = bf.negativeCycle();
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    check(p.length() == 1 && p.front() == p.back() && p.front() == a2,
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          "Wrong negative cycle.");
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  }
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  length[a2] = 0;
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  {
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    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
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    bf.run(n1);
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    check(bf.negativeCycle().empty(),
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          "Negative cycle should not be found.");
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  }
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  length[gr.addArc(n1, n3)] = 5;
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  length[gr.addArc(n4, n3)] = 1;
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  length[gr.addArc(n2, n4)] = 2;
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  length[gr.addArc(n3, n2)] = -4;
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  {
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    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
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    bf.init();
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    bf.addSource(n1);
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    for (int i = 0; i < 4; ++i) {
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      check(bf.negativeCycle().empty(),
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            "Negative cycle should not be found.");
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      bf.processNextRound();
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    }
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    StaticPath<SmartDigraph> p = bf.negativeCycle();
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    check(p.length() == 3, "Wrong negative cycle.");
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    check(length[p.nth(0)] + length[p.nth(1)] + length[p.nth(2)] == -1,
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          "Wrong negative cycle.");
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  }
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}
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int main() {
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  checkBellmanFord<ListDigraph, int>();
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  checkBellmanFord<SmartDigraph, double>();
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  checkBellmanFordNegativeCycle();
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  return 0;
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}