/* -*- C++ -*-

 * demo/dijkstra_demo.cc - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2005 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 LEMON implementation of the 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;

}