fordFulkersonAlgorithm - SeqAn API Documentation

# fn() fordFulkersonAlgorithm
Computes a maximum flow in a directed graph.

Defined in | <seqan/graph_algorithms.h>
Signature | `TValue fordFulkeronAlgorithm(flow, g, source, sink, capacity);`

## Parameters

`flow` | A property map with the flow of each edge.
`g` | A directed graph. Types: Directed Graph
`source` | A source vertex. Types: VertexDescriptor
`sink` | A sink vertex. Types: VertexDescriptor
`capacity` | A property map of edge capacities.

## Return Values

`TValue` | The value of the flow. TValue is the Value tpye of the type of flow.

## Detailed Description

### Example

    #include <iostream>
    #include <seqan/graph_algorithms.h>

    using namespace seqan2;

    int main()
    {
        typedef Graph<Directed<> > TGraph;
        typedef VertexDescriptor<TGraph>::Type TVertexDescriptor;
        typedef Iterator<TGraph, EdgeIterator>::Type TEdgeIterator;
        typedef Size<TGraph>::Type TSize;

        // Create graph with 10 directed edges (0,1), (0,4), ...
        TSize numEdges = 10;
        TVertexDescriptor edges[] = {0, 1, 0, 4, 1, 2, 1, 4, 2, 3, 2, 4, 4, 1, 4, 5, 5, 2, 5, 3};
        TGraph g;
        addEdges(g, edges, numEdges);
        // Print graph.
        std::cout << g << "\n";

        // Create external property map for the edge capacities and assign to the graph.
        String<unsigned int> capMap;
        unsigned capacity[] =    {16, 13, 12, 10, 20, 9, 4, 14, 7, 4};
        assignEdgeMap(capMap, g, capacity);

        // Run the Ford-Fulkerson algorithm for maximum flow computation from source
        // vertex 0 to sink vertex 3.  valF is the value of the flow.
        String<unsigned int> flow;
        unsigned valF = fordFulkersonAlgorithm(flow, g, 0, 3, capMap);

        // Print the result to stdout.
        std::cout << "Ford-Fulkerson (Value of the flow = " << valF << ")\n";
        TEdgeIterator itEdge(g);
        for (; !atEnd(itEdge); goNext(itEdge))
            std::cout << "(" << sourceVertex(itEdge) << "," << targetVertex(itEdge) << "): "
                      << "Flow: " << getProperty(flow, getValue(itEdge)) << ", Capacity: "
                      << getProperty(capMap, getValue(itEdge)) << "\n";

        return 0;
    }

Demo: demos/dox/graph_algorithms/ford_fulkerson_algorithm.cpp

    Adjacency list:
    0 -> 4,1,
    1 -> 4,2,
    2 -> 4,3,
    3 ->
    4 -> 5,1,
    5 -> 3,2,
    Edge list:
    Source: 0,Target: 4 (Id: 1)
    Source: 0,Target: 1 (Id: 0)
    Source: 1,Target: 4 (Id: 3)
    Source: 1,Target: 2 (Id: 2)
    Source: 2,Target: 4 (Id: 5)
    Source: 2,Target: 3 (Id: 4)
    Source: 4,Target: 5 (Id: 7)
    Source: 4,Target: 1 (Id: 6)
    Source: 5,Target: 3 (Id: 9)
    Source: 5,Target: 2 (Id: 8)

    Ford-Fulkerson (Value of the flow = 23)
    (0,4): Flow: 11, Capacity: 13
    (0,1): Flow: 12, Capacity: 16
    (1,4): Flow: 0, Capacity: 10
    (1,2): Flow: 12, Capacity: 12
    (2,4): Flow: 0, Capacity: 9
    (2,3): Flow: 19, Capacity: 20
    (4,5): Flow: 11, Capacity: 14
    (4,1): Flow: 0, Capacity: 4
    (5,3): Flow: 4, Capacity: 4
    (5,2): Flow: 7, Capacity: 7

## Data Races

If not stated otherwise, concurrent invocation is not guaranteed to be thread-safe.

#### Dox Sources

    /*!
     * @fn fordFulkersonAlgorithm
     *
     * @headerfile <seqan/graph_algorithms.h>
     *
     * @brief Computes a maximum flow in a directed graph.
     *
     * @signature TValue fordFulkeronAlgorithm(flow, g, source, sink, capacity);
     *
     * @param[out] flow A property map with the flow of each edge.
     * @param[in] g A directed graph. Types: Directed Graph
     * @param[in] source A source vertex. Types: VertexDescriptor
     * @param[in] sink A sink vertex. Types: VertexDescriptor
     * @param[in] capacity A property map of edge capacities.
     *
     * @return TValue The value of the flow. TValue is the Value tpye of the type of
     *                flow.
     *
     * @section Example
     *
     * @include demos/dox/graph_algorithms/ford_fulkerson_algorithm.cpp
     *
     * @include demos/dox/graph_algorithms/ford_fulkerson_algorithm.cpp.stdout
     */