# fn()primsAlgorithmComputes a minimum spanning tree on a graph.

Defined in ```void primsAlgorithm(predecessor, g, source, weight); ```

## Parameters

 `predecessor` A property map. A property map that represents predecessor relationships among vertices. It determines a minimum spanning tree. An undirected graph. Types: Undirected Graph A source vertex. Types: VertexDescriptor Edge weights.

## Detailed Description

### Example

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

using namespace seqan;

int main()
{
typedef Graph<Undirected<> > TGraph;
typedef VertexDescriptor<TGraph>::Type TVertexDescriptor;
typedef Size<TGraph>::Type TSize;

// Create graph with 14 undirected edges {0,1}, {0,6}, ...
TSize numEdges = 14;
TVertexDescriptor edges[] = {0, 1, 0, 6, 1, 2, 1, 6, 2, 3, 2, 4, 2, 8, 3, 5, 3, 8, 4, 6, 4, 7, 5, 8, 6, 7, 7, 8};
TGraph g;
// Print graph.
std::cout << g << std::endl;

// Fill two external property maps for edge weights and vertex names.
unsigned int weights[] = {4, 8, 8, 11, 7, 2, 4, 9, 14, 7, 6, 10, 1, 2};
char names[] = {'a', 'b', 'c', 'd', 'i', 'e', 'h', 'g', 'f'};
String<int> weightMap;
assignEdgeMap(weightMap, g, weights);
String<char> nameMap;
assignVertexMap(nameMap, g, names);

// Run Prim's algorithm.
String<TVertexDescriptor> predMap;
primsAlgorithm(predMap, g, 0, weightMap);

// Print result to stdout.
std::cout << "Minimum Spanning Tree (Prim's algorithm): \n";
typedef Iterator<TGraph, VertexIterator>::Type TVertexIterator;
TVertexIterator it(g);
while (!atEnd(it))
{
std::cout << "Path from " << getProperty(nameMap, 0) << " to "
<< getProperty(nameMap, getValue(it)) << ": ";
_printPath(g, predMap, (TVertexDescriptor)0, getValue(it), nameMap);
std::cout << "\n";
goNext(it);
}

return 0;
}
```
```Adjacency list:
0 -> 6,1,
1 -> 6,2,0,
2 -> 8,4,3,1,
3 -> 8,5,2,
4 -> 7,6,2,
5 -> 8,3,
6 -> 7,4,1,0,
7 -> 8,6,4,
8 -> 7,5,3,2,
Edge list:
Source: 0,Target: 6 (Id: 1)
Source: 0,Target: 1 (Id: 0)
Source: 1,Target: 6 (Id: 3)
Source: 1,Target: 2 (Id: 2)
Source: 2,Target: 8 (Id: 6)
Source: 2,Target: 4 (Id: 5)
Source: 2,Target: 3 (Id: 4)
Source: 3,Target: 8 (Id: 8)
Source: 3,Target: 5 (Id: 7)
Source: 4,Target: 7 (Id: 10)
Source: 4,Target: 6 (Id: 9)
Source: 5,Target: 8 (Id: 11)
Source: 6,Target: 7 (Id: 12)
Source: 7,Target: 8 (Id: 13)

Minimum Spanning Tree (Prim's algorithm):
Path from a to a: a
Path from a to b: a,b
Path from a to c: a,b,c
Path from a to d: a,b,c,d
Path from a to i: a,b,c,i
Path from a to e: a,b,c,d,e
Path from a to h: a,b,c,f,g,h
Path from a to g: a,b,c,f,g
Path from a to f: a,b,c,f
```

## Data Races

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