# HG changeset patch
# User Peter Kovacs <kpeter@inf.elte.hu>
# Date 1240618361 -7200
# Node ID 7c1324b35d89a2ef91a42e14fae342b651db4549
# Parent 28f58740b6f8f168a125b9af4c4cf141400645d2
Modify the interface of Suurballe (#266, #181)
- Move the parameters s and t from the constructor to the run()
function. It makes the interface capable for multiple run(s,t,k)
calls (possible improvement in the future) and it is more similar
to Dijkstra.
- Simliarly init() and findFlow(k) were replaced by init(s) and
findFlow(t,k). The separation of parameters s and t is for the
future plans of supporting multiple targets with one source node.
For more information see #181.
- LEMON_ASSERT for the Length type (check if it is integer).
- Doc improvements.
- Rearrange query functions.
- Extend test file.
diff -r 28f58740b6f8 -r 7c1324b35d89 lemon/suurballe.h
--- a/lemon/suurballe.h Sat Apr 25 18:25:59 2009 +0200
+++ b/lemon/suurballe.h Sat Apr 25 02:12:41 2009 +0200
@@ -25,6 +25,7 @@
/// nodes having minimum total length.
#include <vector>
+#include <limits>
#include <lemon/bin_heap.h>
#include <lemon/path.h>
#include <lemon/list_graph.h>
@@ -42,22 +43,26 @@
/// finding arc-disjoint paths having minimum total length (cost)
/// from a given source node to a given target node in a digraph.
///
- /// In fact, this implementation is the specialization of the
- /// \ref CapacityScaling "successive shortest path" algorithm.
+ /// Note that this problem is a special case of the \ref min_cost_flow
+ /// "minimum cost flow problem". This implementation is actually an
+ /// efficient specialized version of the \ref CapacityScaling
+ /// "Successive Shortest Path" algorithm directly for this problem.
+ /// Therefore this class provides query functions for flow values and
+ /// node potentials (the dual solution) just like the minimum cost flow
+ /// algorithms.
///
/// \tparam GR The digraph type the algorithm runs on.
- /// The default value is \c ListDigraph.
- /// \tparam LEN The type of the length (cost) map.
- /// The default value is <tt>Digraph::ArcMap<int></tt>.
+ /// \tparam LEN The type of the length map.
+ /// The default value is <tt>GR::ArcMap<int></tt>.
///
/// \warning Length values should be \e non-negative \e integers.
///
/// \note For finding node-disjoint paths this algorithm can be used
- /// with \ref SplitNodes.
+ /// along with the \ref SplitNodes adaptor.
#ifdef DOXYGEN
template <typename GR, typename LEN>
#else
- template < typename GR = ListDigraph,
+ template < typename GR,
typename LEN = typename GR::template ArcMap<int> >
#endif
class Suurballe
@@ -75,23 +80,28 @@
typedef LEN LengthMap;
/// The type of the lengths.
typedef typename LengthMap::Value Length;
+#ifdef DOXYGEN
+ /// The type of the flow map.
+ typedef GR::ArcMap<int> FlowMap;
+ /// The type of the potential map.
+ typedef GR::NodeMap<Length> PotentialMap;
+#else
/// The type of the flow map.
typedef typename Digraph::template ArcMap<int> FlowMap;
/// The type of the potential map.
typedef typename Digraph::template NodeMap<Length> PotentialMap;
+#endif
+
/// The type of the path structures.
- typedef SimplePath<Digraph> Path;
+ typedef SimplePath<GR> Path;
private:
- /// \brief Special implementation of the Dijkstra algorithm
- /// for finding shortest paths in the residual network.
- ///
- /// \ref ResidualDijkstra is a special implementation of the
- /// \ref Dijkstra algorithm for finding shortest paths in the
- /// residual network of the digraph with respect to the reduced arc
- /// lengths and modifying the node potentials according to the
- /// distance of the nodes.
+ // ResidualDijkstra is a special implementation of the
+ // Dijkstra algorithm for finding shortest paths in the
+ // residual network with respect to the reduced arc lengths
+ // and modifying the node potentials according to the
+ // distance of the nodes.
class ResidualDijkstra
{
typedef typename Digraph::template NodeMap<int> HeapCrossRef;
@@ -120,14 +130,14 @@
public:
/// Constructor.
- ResidualDijkstra( const Digraph &digraph,
+ ResidualDijkstra( const Digraph &graph,
const FlowMap &flow,
const LengthMap &length,
PotentialMap &potential,
PredMap &pred,
Node s, Node t ) :
- _graph(digraph), _flow(flow), _length(length), _potential(potential),
- _dist(digraph), _pred(pred), _s(s), _t(t) {}
+ _graph(graph), _flow(flow), _length(length), _potential(potential),
+ _dist(graph), _pred(pred), _s(s), _t(t) {}
/// \brief Run the algorithm. It returns \c true if a path is found
/// from the source node to the target node.
@@ -236,16 +246,16 @@
///
/// Constructor.
///
- /// \param digraph The digraph the algorithm runs on.
+ /// \param graph The digraph the algorithm runs on.
/// \param length The length (cost) values of the arcs.
- /// \param s The source node.
- /// \param t The target node.
- Suurballe( const Digraph &digraph,
- const LengthMap &length,
- Node s, Node t ) :
- _graph(digraph), _length(length), _flow(0), _local_flow(false),
- _potential(0), _local_potential(false), _source(s), _target(t),
- _pred(digraph) {}
+ Suurballe( const Digraph &graph,
+ const LengthMap &length ) :
+ _graph(graph), _length(length), _flow(0), _local_flow(false),
+ _potential(0), _local_potential(false), _pred(graph)
+ {
+ LEMON_ASSERT(std::numeric_limits<Length>::is_integer,
+ "The length type of Suurballe must be integer");
+ }
/// Destructor.
~Suurballe() {
@@ -257,9 +267,12 @@
/// \brief Set the flow map.
///
/// This function sets the flow map.
+ /// If it is not used before calling \ref run() or \ref init(),
+ /// an instance will be allocated automatically. The destructor
+ /// deallocates this automatically allocated map, of course.
///
- /// The found flow contains only 0 and 1 values. It is the union of
- /// the found arc-disjoint paths.
+ /// The found flow contains only 0 and 1 values, since it is the
+ /// union of the found arc-disjoint paths.
///
/// \return <tt>(*this)</tt>
Suurballe& flowMap(FlowMap &map) {
@@ -274,9 +287,12 @@
/// \brief Set the potential map.
///
/// This function sets the potential map.
+ /// If it is not used before calling \ref run() or \ref init(),
+ /// an instance will be allocated automatically. The destructor
+ /// deallocates this automatically allocated map, of course.
///
- /// The potentials provide the dual solution of the underlying
- /// minimum cost flow problem.
+ /// The node potentials provide the dual solution of the underlying
+ /// \ref min_cost_flow "minimum cost flow problem".
///
/// \return <tt>(*this)</tt>
Suurballe& potentialMap(PotentialMap &map) {
@@ -301,22 +317,24 @@
///
/// This function runs the algorithm.
///
+ /// \param s The source node.
+ /// \param t The target node.
/// \param k The number of paths to be found.
///
/// \return \c k if there are at least \c k arc-disjoint paths from
/// \c s to \c t in the digraph. Otherwise it returns the number of
/// arc-disjoint paths found.
///
- /// \note Apart from the return value, <tt>s.run(k)</tt> is just a
- /// shortcut of the following code.
+ /// \note Apart from the return value, <tt>s.run(s, t, k)</tt> is
+ /// just a shortcut of the following code.
/// \code
- /// s.init();
- /// s.findFlow(k);
+ /// s.init(s);
+ /// s.findFlow(t, k);
/// s.findPaths();
/// \endcode
- int run(int k = 2) {
- init();
- findFlow(k);
+ int run(const Node& s, const Node& t, int k = 2) {
+ init(s);
+ findFlow(t, k);
findPaths();
return _path_num;
}
@@ -324,7 +342,11 @@
/// \brief Initialize the algorithm.
///
/// This function initializes the algorithm.
- void init() {
+ ///
+ /// \param s The source node.
+ void init(const Node& s) {
+ _source = s;
+
// Initialize maps
if (!_flow) {
_flow = new FlowMap(_graph);
@@ -336,25 +358,28 @@
}
for (ArcIt e(_graph); e != INVALID; ++e) (*_flow)[e] = 0;
for (NodeIt n(_graph); n != INVALID; ++n) (*_potential)[n] = 0;
-
- _dijkstra = new ResidualDijkstra( _graph, *_flow, _length,
- *_potential, _pred,
- _source, _target );
}
- /// \brief Execute the successive shortest path algorithm to find
- /// an optimal flow.
+ /// \brief Execute the algorithm to find an optimal flow.
///
/// This function executes the successive shortest path algorithm to
- /// find a minimum cost flow, which is the union of \c k or less
+ /// find a minimum cost flow, which is the union of \c k (or less)
/// arc-disjoint paths.
///
+ /// \param t The target node.
+ /// \param k The number of paths to be found.
+ ///
/// \return \c k if there are at least \c k arc-disjoint paths from
- /// \c s to \c t in the digraph. Otherwise it returns the number of
- /// arc-disjoint paths found.
+ /// the source node to the given node \c t in the digraph.
+ /// Otherwise it returns the number of arc-disjoint paths found.
///
/// \pre \ref init() must be called before using this function.
- int findFlow(int k = 2) {
+ int findFlow(const Node& t, int k = 2) {
+ _target = t;
+ _dijkstra =
+ new ResidualDijkstra( _graph, *_flow, _length, *_potential, _pred,
+ _source, _target );
+
// Find shortest paths
_path_num = 0;
while (_path_num < k) {
@@ -380,13 +405,12 @@
/// \brief Compute the paths from the flow.
///
- /// This function computes the paths from the flow.
+ /// This function computes the paths from the found minimum cost flow,
+ /// which is the union of some arc-disjoint paths.
///
/// \pre \ref init() and \ref findFlow() must be called before using
/// this function.
void findPaths() {
- // Create the residual flow map (the union of the paths not found
- // so far)
FlowMap res_flow(_graph);
for(ArcIt a(_graph); a != INVALID; ++a) res_flow[a] = (*_flow)[a];
@@ -413,10 +437,37 @@
/// @{
- /// \brief Return a const reference to the arc map storing the
+ /// \brief Return the total length of the found paths.
+ ///
+ /// This function returns the total length of the found paths, i.e.
+ /// the total cost of the found flow.
+ /// The complexity of the function is O(e).
+ ///
+ /// \pre \ref run() or \ref findFlow() must be called before using
+ /// this function.
+ Length totalLength() const {
+ Length c = 0;
+ for (ArcIt e(_graph); e != INVALID; ++e)
+ c += (*_flow)[e] * _length[e];
+ return c;
+ }
+
+ /// \brief Return the flow value on the given arc.
+ ///
+ /// This function returns the flow value on the given arc.
+ /// It is \c 1 if the arc is involved in one of the found arc-disjoint
+ /// paths, otherwise it is \c 0.
+ ///
+ /// \pre \ref run() or \ref findFlow() must be called before using
+ /// this function.
+ int flow(const Arc& arc) const {
+ return (*_flow)[arc];
+ }
+
+ /// \brief Return a const reference to an arc map storing the
/// found flow.
///
- /// This function returns a const reference to the arc map storing
+ /// This function returns a const reference to an arc map storing
/// the flow that is the union of the found arc-disjoint paths.
///
/// \pre \ref run() or \ref findFlow() must be called before using
@@ -425,34 +476,11 @@
return *_flow;
}
- /// \brief Return a const reference to the node map storing the
- /// found potentials (the dual solution).
- ///
- /// This function returns a const reference to the node map storing
- /// the found potentials that provide the dual solution of the
- /// underlying minimum cost flow problem.
- ///
- /// \pre \ref run() or \ref findFlow() must be called before using
- /// this function.
- const PotentialMap& potentialMap() const {
- return *_potential;
- }
-
- /// \brief Return the flow on the given arc.
- ///
- /// This function returns the flow on the given arc.
- /// It is \c 1 if the arc is involved in one of the found paths,
- /// otherwise it is \c 0.
- ///
- /// \pre \ref run() or \ref findFlow() must be called before using
- /// this function.
- int flow(const Arc& arc) const {
- return (*_flow)[arc];
- }
-
/// \brief Return the potential of the given node.
///
/// This function returns the potential of the given node.
+ /// The node potentials provide the dual solution of the
+ /// underlying \ref min_cost_flow "minimum cost flow problem".
///
/// \pre \ref run() or \ref findFlow() must be called before using
/// this function.
@@ -460,18 +488,17 @@
return (*_potential)[node];
}
- /// \brief Return the total length (cost) of the found paths (flow).
+ /// \brief Return a const reference to a node map storing the
+ /// found potentials (the dual solution).
///
- /// This function returns the total length (cost) of the found paths
- /// (flow). The complexity of the function is O(e).
+ /// This function returns a const reference to a node map storing
+ /// the found potentials that provide the dual solution of the
+ /// underlying \ref min_cost_flow "minimum cost flow problem".
///
/// \pre \ref run() or \ref findFlow() must be called before using
/// this function.
- Length totalLength() const {
- Length c = 0;
- for (ArcIt e(_graph); e != INVALID; ++e)
- c += (*_flow)[e] * _length[e];
- return c;
+ const PotentialMap& potentialMap() const {
+ return *_potential;
}
/// \brief Return the number of the found paths.
@@ -488,7 +515,7 @@
///
/// This function returns a const reference to the specified path.
///
- /// \param i The function returns the \c i-th path.
+ /// \param i The function returns the <tt>i</tt>-th path.
/// \c i must be between \c 0 and <tt>%pathNum()-1</tt>.
///
/// \pre \ref run() or \ref findPaths() must be called before using
diff -r 28f58740b6f8 -r 7c1324b35d89 test/suurballe_test.cc
--- a/test/suurballe_test.cc Sat Apr 25 18:25:59 2009 +0200
+++ b/test/suurballe_test.cc Sat Apr 25 02:12:41 2009 +0200
@@ -22,6 +22,7 @@
#include <lemon/lgf_reader.h>
#include <lemon/path.h>
#include <lemon/suurballe.h>
+#include <lemon/concepts/digraph.h>
#include "test_tools.h"
@@ -29,47 +30,97 @@
char test_lgf[] =
"@nodes\n"
- "label supply1 supply2 supply3\n"
- "1 0 20 27\n"
- "2 0 -4 0\n"
- "3 0 0 0\n"
- "4 0 0 0\n"
- "5 0 9 0\n"
- "6 0 -6 0\n"
- "7 0 0 0\n"
- "8 0 0 0\n"
- "9 0 3 0\n"
- "10 0 -2 0\n"
- "11 0 0 0\n"
- "12 0 -20 -27\n"
+ "label\n"
+ "1\n"
+ "2\n"
+ "3\n"
+ "4\n"
+ "5\n"
+ "6\n"
+ "7\n"
+ "8\n"
+ "9\n"
+ "10\n"
+ "11\n"
+ "12\n"
"@arcs\n"
- " cost capacity lower1 lower2\n"
- " 1 2 70 11 0 8\n"
- " 1 3 150 3 0 1\n"
- " 1 4 80 15 0 2\n"
- " 2 8 80 12 0 0\n"
- " 3 5 140 5 0 3\n"
- " 4 6 60 10 0 1\n"
- " 4 7 80 2 0 0\n"
- " 4 8 110 3 0 0\n"
- " 5 7 60 14 0 0\n"
- " 5 11 120 12 0 0\n"
- " 6 3 0 3 0 0\n"
- " 6 9 140 4 0 0\n"
- " 6 10 90 8 0 0\n"
- " 7 1 30 5 0 0\n"
- " 8 12 60 16 0 4\n"
- " 9 12 50 6 0 0\n"
- "10 12 70 13 0 5\n"
- "10 2 100 7 0 0\n"
- "10 7 60 10 0 0\n"
- "11 10 20 14 0 6\n"
- "12 11 30 10 0 0\n"
+ " length\n"
+ " 1 2 70\n"
+ " 1 3 150\n"
+ " 1 4 80\n"
+ " 2 8 80\n"
+ " 3 5 140\n"
+ " 4 6 60\n"
+ " 4 7 80\n"
+ " 4 8 110\n"
+ " 5 7 60\n"
+ " 5 11 120\n"
+ " 6 3 0\n"
+ " 6 9 140\n"
+ " 6 10 90\n"
+ " 7 1 30\n"
+ " 8 12 60\n"
+ " 9 12 50\n"
+ "10 12 70\n"
+ "10 2 100\n"
+ "10 7 60\n"
+ "11 10 20\n"
+ "12 11 30\n"
"@attributes\n"
"source 1\n"
"target 12\n"
"@end\n";
+// Check the interface of Suurballe
+void checkSuurballeCompile()
+{
+ typedef int VType;
+ typedef concepts::Digraph Digraph;
+
+ typedef Digraph::Node Node;
+ typedef Digraph::Arc Arc;
+ typedef concepts::ReadMap<Arc, VType> LengthMap;
+
+ typedef Suurballe<Digraph, LengthMap> SuurballeType;
+
+ Digraph g;
+ Node n;
+ Arc e;
+ LengthMap len;
+ SuurballeType::FlowMap flow(g);
+ SuurballeType::PotentialMap pi(g);
+
+ SuurballeType suurb_test(g, len);
+ const SuurballeType& const_suurb_test = suurb_test;
+
+ suurb_test
+ .flowMap(flow)
+ .potentialMap(pi);
+
+ int k;
+ k = suurb_test.run(n, n);
+ k = suurb_test.run(n, n, k);
+ suurb_test.init(n);
+ k = suurb_test.findFlow(n);
+ k = suurb_test.findFlow(n, k);
+ suurb_test.findPaths();
+
+ int f;
+ VType c;
+ c = const_suurb_test.totalLength();
+ f = const_suurb_test.flow(e);
+ const SuurballeType::FlowMap& fm =
+ const_suurb_test.flowMap();
+ c = const_suurb_test.potential(n);
+ const SuurballeType::PotentialMap& pm =
+ const_suurb_test.potentialMap();
+ k = const_suurb_test.pathNum();
+ Path<Digraph> p = const_suurb_test.path(k);
+
+ ignore_unused_variable_warning(fm);
+ ignore_unused_variable_warning(pm);
+}
+
// Check the feasibility of the flow
template <typename Digraph, typename FlowMap>
bool checkFlow( const Digraph& gr, const FlowMap& flow,
@@ -118,7 +169,6 @@
bool checkPath( const Digraph& gr, const Path& path,
typename Digraph::Node s, typename Digraph::Node t)
{
- // Check the "Complementary Slackness" optimality condition
TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
Node n = s;
for (int i = 0; i < path.length(); ++i) {
@@ -136,58 +186,55 @@
// Read the test digraph
ListDigraph digraph;
ListDigraph::ArcMap<int> length(digraph);
- Node source, target;
+ Node s, t;
std::istringstream input(test_lgf);
DigraphReader<ListDigraph>(digraph, input).
- arcMap("cost", length).
- node("source", source).
- node("target", target).
+ arcMap("length", length).
+ node("source", s).
+ node("target", t).
run();
// Find 2 paths
{
- Suurballe<ListDigraph> suurballe(digraph, length, source, target);
- check(suurballe.run(2) == 2, "Wrong number of paths");
- check(checkFlow(digraph, suurballe.flowMap(), source, target, 2),
+ Suurballe<ListDigraph> suurballe(digraph, length);
+ check(suurballe.run(s, t) == 2, "Wrong number of paths");
+ check(checkFlow(digraph, suurballe.flowMap(), s, t, 2),
"The flow is not feasible");
check(suurballe.totalLength() == 510, "The flow is not optimal");
check(checkOptimality(digraph, length, suurballe.flowMap(),
suurballe.potentialMap()),
"Wrong potentials");
for (int i = 0; i < suurballe.pathNum(); ++i)
- check(checkPath(digraph, suurballe.path(i), source, target),
- "Wrong path");
+ check(checkPath(digraph, suurballe.path(i), s, t), "Wrong path");
}
// Find 3 paths
{
- Suurballe<ListDigraph> suurballe(digraph, length, source, target);
- check(suurballe.run(3) == 3, "Wrong number of paths");
- check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
+ Suurballe<ListDigraph> suurballe(digraph, length);
+ check(suurballe.run(s, t, 3) == 3, "Wrong number of paths");
+ check(checkFlow(digraph, suurballe.flowMap(), s, t, 3),
"The flow is not feasible");
check(suurballe.totalLength() == 1040, "The flow is not optimal");
check(checkOptimality(digraph, length, suurballe.flowMap(),
suurballe.potentialMap()),
"Wrong potentials");
for (int i = 0; i < suurballe.pathNum(); ++i)
- check(checkPath(digraph, suurballe.path(i), source, target),
- "Wrong path");
+ check(checkPath(digraph, suurballe.path(i), s, t), "Wrong path");
}
// Find 5 paths (only 3 can be found)
{
- Suurballe<ListDigraph> suurballe(digraph, length, source, target);
- check(suurballe.run(5) == 3, "Wrong number of paths");
- check(checkFlow(digraph, suurballe.flowMap(), source, target, 3),
+ Suurballe<ListDigraph> suurballe(digraph, length);
+ check(suurballe.run(s, t, 5) == 3, "Wrong number of paths");
+ check(checkFlow(digraph, suurballe.flowMap(), s, t, 3),
"The flow is not feasible");
check(suurballe.totalLength() == 1040, "The flow is not optimal");
check(checkOptimality(digraph, length, suurballe.flowMap(),
suurballe.potentialMap()),
"Wrong potentials");
for (int i = 0; i < suurballe.pathNum(); ++i)
- check(checkPath(digraph, suurballe.path(i), source, target),
- "Wrong path");
+ check(checkPath(digraph, suurballe.path(i), s, t), "Wrong path");
}
return 0;
diff -r 28f58740b6f8 -r 7c1324b35d89 tools/lgf-gen.cc
--- a/tools/lgf-gen.cc Sat Apr 25 18:25:59 2009 +0200
+++ b/tools/lgf-gen.cc Sat Apr 25 02:12:41 2009 +0200
@@ -480,8 +480,8 @@
Node b=g.v(*ei);
g.erase(*ei);
ConstMap<Arc,int> cegy(1);
- Suurballe<ListGraph,ConstMap<Arc,int> > sur(g,cegy,a,b);
- int k=sur.run(2);
+ Suurballe<ListGraph,ConstMap<Arc,int> > sur(g,cegy);
+ int k=sur.run(a,b,2);
if(k<2 || sur.totalLength()>d)
g.addEdge(a,b);
else cnt++;
@@ -511,9 +511,8 @@
Edge ne;
if(e==INVALID) {
ConstMap<Arc,int> cegy(1);
- Suurballe<ListGraph,ConstMap<Arc,int> >
- sur(g,cegy,pi->a,pi->b);
- int k=sur.run(2);
+ Suurballe<ListGraph,ConstMap<Arc,int> > sur(g,cegy);
+ int k=sur.run(pi->a,pi->b,2);
if(k<2 || sur.totalLength()>d)
{
ne=g.addEdge(pi->a,pi->b);