You can download LEMON from ...

 You can download LEMON from the following web site:

 Helloworld program

 If you have installed LEMON on your system you can paste the following code

 Link to quicktour

 segment into a file to have a first working program that uses library LEMON.

 \code

 #include <iostream>

 #include <lemon/list_graph.h>

 using namespace lemon;

 int main()

 {

   typedef ListGraph Graph;

   typedef Graph::Edge Edge;

   typedef Graph::InEdgeIt InEdgeIt;

   typedef Graph::OutEdgeIt OutEdgeIt;

   typedef Graph::EdgeIt EdgeIt;

   typedef Graph::Node Node;

   typedef Graph::NodeIt NodeIt;

   Graph g;

   for (int i = 0; i < 3; i++)

     g.addNode();

   for (NodeIt i(g); i!=INVALID; ++i)

     for (NodeIt j(g); j!=INVALID; ++j)

       if (i != j) g.addEdge(i, j);

   std::cout << "Nodes:";

   for (NodeIt i(g); i!=INVALID; ++i)

     std::cout << " " << g.id(i);

   std::cout << std::endl;

   std::cout << "Edges:";

   for (EdgeIt i(g); i!=INVALID; ++i)

     std::cout << " (" << g.id(g.source(i)) << "," << g.id(g.target(i)) << ")";

   std::cout << std::endl;

 \endcode

 ListGraph is one of LEMON's graph classes. It is based on linked lists,

 therefore iterating throuh its edges and nodes is fast.

 After some convenient typedefs we create a graph and add three nodes to it.

 Then we add edges to it to form a complete graph.

 Then we iterate through all nodes of the graph. We use a constructor of the

 node iterator to initialize it to the first node. The operator++ is used to

 step to the next node. Using operator++ on the iterator pointing to the last

 node invalidates the iterator i.e. sets its value to

 \ref lemon::INVALID "INVALID". This is what we exploit in the stop condition.

 We can also iterate through all edges of the graph very similarly. The 

 \c target and

 \c source member functions can be used to access the endpoints of an edge.

 The previous code fragment prints out the following:

 \code

 Nodes: 2 1 0

 Edges: (0,2) (1,2) (0,1) (2,1) (1,0) (2,0)

 \endcode

 If you want to see more features, go to the \ref quicktour "Quick Tour to

 LEMON", if you want to see see some demo programs then go to our 

 \ref demoprograms "Demo Programs" page!