test/min_cost_arborescence_test.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Fri, 03 Apr 2009 18:59:15 +0200
changeset 655 6ac5d9ae1d3d
child 672 029a48052c67
permissions -rw-r--r--
Support real types + numerical stability fix in NS (#254)

- Real types are supported by appropriate inicialization.
- A feature of the XTI spanning tree structure is removed to ensure
numerical stability (could cause problems using integer types).
The node potentials are updated always on the lower subtree,
in order to prevent overflow problems.
The former method isn't notably faster during to our tests.
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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) 2003-2008
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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 <iostream>
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#include <set>
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#include <vector>
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#include <iterator>
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#include <lemon/smart_graph.h>
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#include <lemon/min_cost_arborescence.h>
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#include <lemon/lgf_reader.h>
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#include "test_tools.h"
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using namespace lemon;
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using namespace std;
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const 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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  "5\n"
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  "6\n"
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  "7\n"
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  "8\n"
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  "9\n"
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  "@arcs\n"
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  "     label  cost\n"
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  "1 8  0      107\n"
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  "0 3  1      70\n"
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  "2 1  2      46\n"
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  "4 1  3      28\n"
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  "4 4  4      91\n"
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  "3 9  5      76\n"
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  "9 8  6      61\n"
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  "8 1  7      39\n"
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  "9 8  8      74\n"
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  "8 0  9      39\n"
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  "4 3  10     45\n"
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  "2 2  11     34\n"
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  "0 1  12     100\n"
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  "6 3  13     95\n"
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  "4 1  14     22\n"
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  "1 1  15     31\n"
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  "7 2  16     51\n"
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  "2 6  17     29\n"
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  "8 3  18     115\n"
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  "6 9  19     32\n"
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  "1 1  20     60\n"
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  "0 3  21     40\n"
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  "@attributes\n"
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  "source 0\n";
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int main() {
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  typedef SmartDigraph Digraph;
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  DIGRAPH_TYPEDEFS(Digraph);
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  typedef Digraph::ArcMap<double> CostMap;
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  Digraph digraph;
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  CostMap cost(digraph);
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  Node source;
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  std::istringstream is(test_lgf);
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  digraphReader(digraph, is).
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    arcMap("cost", cost).
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    node("source", source).run();
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  MinCostArborescence<Digraph, CostMap> mca(digraph, cost);
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  mca.run(source);
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  vector<pair<double, set<Node> > > dualSolution(mca.dualNum());
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  for (int i = 0; i < mca.dualNum(); ++i) {
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    dualSolution[i].first = mca.dualValue(i);
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    for (MinCostArborescence<Digraph, CostMap>::DualIt it(mca, i);
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         it != INVALID; ++it) {
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      dualSolution[i].second.insert(it);
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    }
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  }
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  for (ArcIt it(digraph); it != INVALID; ++it) {
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    if (mca.reached(digraph.source(it))) {
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      double sum = 0.0;
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      for (int i = 0; i < int(dualSolution.size()); ++i) {
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        if (dualSolution[i].second.find(digraph.target(it))
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            != dualSolution[i].second.end() &&
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            dualSolution[i].second.find(digraph.source(it))
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            == dualSolution[i].second.end()) {
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          sum += dualSolution[i].first;
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        }
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      }
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      if (mca.arborescence(it)) {
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        check(sum == cost[it], "INVALID DUAL");
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      }
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      check(sum <= cost[it], "INVALID DUAL");
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    }
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  }
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  check(mca.dualValue() == mca.arborescenceValue(), "INVALID DUAL");
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  check(mca.reached(source), "INVALID ARBORESCENCE");
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  for (ArcIt a(digraph); a != INVALID; ++a) {
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    check(!mca.reached(digraph.source(a)) ||
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          mca.reached(digraph.target(a)), "INVALID ARBORESCENCE");
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  }
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  for (NodeIt n(digraph); n != INVALID; ++n) {
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    if (!mca.reached(n)) continue;
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    int cnt = 0;
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    for (InArcIt a(digraph, n); a != INVALID; ++a) {
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      if (mca.arborescence(a)) {
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        check(mca.pred(n) == a, "INVALID ARBORESCENCE");
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        ++cnt;
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      }
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    }
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    check((n == source ? cnt == 0 : cnt == 1), "INVALID ARBORESCENCE");
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  }
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  Digraph::ArcMap<bool> arborescence(digraph);
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  check(mca.arborescenceValue() ==
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        minCostArborescence(digraph, cost, source, arborescence),
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        "WRONG FUNCTION");
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  return 0;
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}