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// ==========================================================================
// SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2018, Knut Reinert, FU Berlin
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of Knut Reinert or the FU Berlin nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL KNUT REINERT OR THE FU BERLIN BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
//
// ==========================================================================
// Author: Manuel Holtgrewe <manuel.holtgrewe@fu-berlin.de>
// ==========================================================================
// Implementation of the Connected-Components algorithm.
// ==========================================================================
#ifndef INCLUDE_SEQAN_GRAPH_ALGORITHMS_CONNECTED_COMPONENTS_H_
#define INCLUDE_SEQAN_GRAPH_ALGORITHMS_CONNECTED_COMPONENTS_H_
namespace seqan {
// ============================================================================
// Forwards
// ============================================================================
// ============================================================================
// Tags, Classes, Enums
// ============================================================================
// ============================================================================
// Metafunctions
// ============================================================================
// ============================================================================
// Functions
// ============================================================================
// ----------------------------------------------------------------------------
// Function connectedComponents()
// ----------------------------------------------------------------------------
/*!
* @fn connectedComponents
*
* @headerfile <seqan/graph_algorithms.h>
*
* @brief Decomposes an undirected graph into its connected components.
*
* @signature TSize connectedComponents(components, g);
*
* @param[out] components
* A property map. Each vertex is mapped to a component id. If two vertices share the same id
* they are in the same component.
* @param[in] g An undirected graph. Types: Undirected Graph
*
* @return TSize The number of components.
*
* @section Examples
*
* A simple example on how to use this function.
*
* @code{.cpp}
* // Build Input.
* Graph<Undirected<> > graph;
* for (unsigned i = 0; i < 5; ++i)
* addVertex(graph);
* addEdge(graph, 0, 1);
* addEdge(graph, 0, 3);
* addEdge(graph, 2, 4);
* String<unsigned> components;
* unsigned numComponents = 0;
*
* // Call Algorithm.
* numComponents = connectedComponents(g, components);
*
* // Print Result.
* std::cout << "Number of components: " << numComponents << std::endl;
* std::cout << std::endl << "Vertex -> Component" << std::endl;
* for (unsigned i = 0; i < length(components); ++i)
* std::cout << i << " -> " << components[i] << std::endl;
* @endcode
* The output now is:
*
* @code{.console}
* Number of components: 2
*
* Vertex -> Component
* 0 -> 0
* 1 -> 0
* 2 -> 1
* 3 -> 0
* 4 -> 1
* @endcode
*/
template <typename TSpec, typename TComponents>
typename Size<Graph<TSpec> >::Type
connectedComponents(TComponents & components,
Graph<TSpec> const & g)
{
typedef typename VertexDescriptor<Graph<TSpec> >::Type TVertexDescriptor;
// Initialize Union-Find data structure.
UnionFind<TVertexDescriptor> uf;
resizeVertexMap(uf, g);
// Use Union-Find data structure to compute connected components.
for (typename Iterator<Graph<TSpec>, EdgeIterator>::Type it(g); !atEnd(it); goNext(it))
joinSets(uf, findSet(uf, sourceVertex(it)), findSet(uf, targetVertex(it)));
// Build final component map.
resizeVertexMap(components, g);
unsigned c = 0;
std::map<TVertexDescriptor, unsigned> reprToComponent;
for (typename Iterator<Graph<TSpec>, VertexIterator>::Type it(g); !atEnd(it); goNext(it))
{
TVertexDescriptor v = findSet(uf, *it);
// Build mapping from representant to component id on the fly.
if (!reprToComponent.count(v))
reprToComponent[v] = c++;
assignProperty(components, *it, reprToComponent[v]);
}
return c;
}
} // namespace seqan
#endif // #ifndef INCLUDE_SEQAN_GRAPH_ALGORITHMS_CONNECTED_COMPONENTS_H_
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