/* -*- C++ -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2003-2008

  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 ///\ingroup demos

 ///\file

 ///\brief Demonstrating the usage of LEMON's Dijkstra algorithm

 ///

 /// Dijkstra's algorithm computes shortest paths between two nodes in

 /// a graph with edge lengths. Here we only show some of the

 /// facilities supplied by our implementation: for the detailed

 /// documentation of the LEMON Dijkstra class read \ref lemon::Dijkstra "this".

 ///

 /// \include dijkstra_demo.cc

 #include <iostream>

 #include <lemon/list_graph.h>

 #include <lemon/dijkstra.h>

 using namespace lemon;

 int main (int, char*[])

 {

     typedef ListGraph Graph;

     typedef Graph::Node Node;

     typedef Graph::Edge Edge;

     typedef Graph::EdgeMap<int> LengthMap;

     Graph g;

     //An example from Ahuja's book

     Node s=g.addNode();

     Node v2=g.addNode();

     Node v3=g.addNode();

     Node v4=g.addNode();

     Node v5=g.addNode();

     Node t=g.addNode();

     Edge s_v2=g.addEdge(s, v2);

     Edge s_v3=g.addEdge(s, v3);

     Edge v2_v4=g.addEdge(v2, v4);

     Edge v2_v5=g.addEdge(v2, v5);

     Edge v3_v5=g.addEdge(v3, v5);

     Edge v4_t=g.addEdge(v4, t);

     Edge v5_t=g.addEdge(v5, t);

     LengthMap len(g);

     len.set(s_v2, 10);

     len.set(s_v3, 10);

     len.set(v2_v4, 5);

     len.set(v2_v5, 8);

     len.set(v3_v5, 5);

     len.set(v4_t, 8);

     len.set(v5_t, 8);

     std::cout << "This program is a simple demo of the LEMON Dijkstra class."

 	      << std::endl;

     std::cout <<

       "We calculate the shortest path from node s to node t in a graph."

 	      << std::endl;

     std::cout << std::endl;

     std::cout << "The id of s is " << g.id(s)<< ", the id of t is "

 	      << g.id(t) << "." << std::endl;

     std::cout << "Dijkstra algorithm demo..." << std::endl;

     Dijkstra<Graph, LengthMap> dijkstra_test(g,len);

     dijkstra_test.run(s);

     std::cout << "The distance of node t from node s: "

 	      << dijkstra_test.dist(t) << std::endl;

     std::cout << "The shortest path from s to t goes through the following "

 	      << "nodes (the first one is t, the last one is s): "

 	      << std::endl;

     for (Node v=t;v != s; v=dijkstra_test.predNode(v)) {

       std::cout << g.id(v) << "<-";

     }

     std::cout << g.id(s) << std::endl;	

     return 0;

 }