/* -*- C++ -*-

  * demo/kruskal_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 Minimum weight spanning tree by Kruskal algorithm (demo).

 ///

 /// This demo program shows how to find a minimum weight spanning tree

 /// in a graph by using the Kruskal algorithm. 

 #include <iostream>

 #include <vector>

 #include <lemon/maps.h>

 #include <lemon/kruskal.h>

 #include <lemon/list_graph.h>

 using namespace std;

 using namespace lemon;

 int main() {

   typedef ListGraph::Node Node;

   typedef ListGraph::Edge Edge;

   typedef ListGraph::NodeIt NodeIt;

   typedef ListGraph::EdgeIt EdgeIt;

   ListGraph g;

   //Make an example graph g.

   Node s=g.addNode();

   Node v1=g.addNode();

   Node v2=g.addNode();

   Node v3=g.addNode();

   Node v4=g.addNode();

   Node t=g.addNode();

   Edge e1 = g.addEdge(s, v1);

   Edge e2 = g.addEdge(s, v2);

   Edge e3 = g.addEdge(v1, v2);

   Edge e4 = g.addEdge(v2, v1);

   Edge e5 = g.addEdge(v1, v3);

   Edge e6 = g.addEdge(v3, v2);

   Edge e7 = g.addEdge(v2, v4);

   Edge e8 = g.addEdge(v4, v3);

   Edge e9 = g.addEdge(v3, t);

   Edge e10 = g.addEdge(v4, t);

   //Make the input for the kruskal.

   typedef ListGraph::EdgeMap<int> ECostMap;

   ECostMap edge_cost_map(g);

   // Fill the edge_cost_map. 

   edge_cost_map.set(e1, -10);

   edge_cost_map.set(e2, -9);

   edge_cost_map.set(e3, -8);

   edge_cost_map.set(e4, -7);

   edge_cost_map.set(e5, -6);

   edge_cost_map.set(e6, -5);

   edge_cost_map.set(e7, -4);

   edge_cost_map.set(e8, -3);

   edge_cost_map.set(e9, -2);

   edge_cost_map.set(e10, -1);

   // Make the map or the vector, which will contain the edges of the minimum

   // spanning tree.

   typedef ListGraph::EdgeMap<bool> EBoolMap;

   EBoolMap tree_map(g);

   vector<Edge> tree_edge_vec;

   //Kruskal Algorithm.  

   //Input: a graph (g); a costmap of the graph (edge_cost_map); a

   //boolmap (tree_map) or a vector (tree_edge_vec) to store the edges

   //of the output tree;

   //Output: it gives back the value of the minimum spanning tree, and

   //set true for the edges of the tree in the edgemap tree_map or

   //store the edges of the tree in the vector tree_edge_vec;

   // Kruskal with boolmap;

   std::cout << "The weight of the minimum spanning tree is " << 

     kruskal(g, edge_cost_map, tree_map)<<std::endl;

   int k=0;

   std::cout << "The edges of the tree:" ;

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

     if (tree_map[i]) { 

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

       ++k;

     }

   }

   std::cout << std::endl;

   std::cout << "The size of the tree is: "<< k << std::endl;

   // Kruskal with vector;

   std::cout << "The weight of the minimum spanning tree again is " << 

     kruskal(g, edge_cost_map, std::back_inserter(tree_edge_vec)) <<std::endl;

   std::cout << "The edges of the tree again: " ;

   for(int i=tree_edge_vec.size()-1; i>=0;  i--)

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

   std::cout << std::endl;

   std::cout << "The size of the tree again is: "<< tree_edge_vec.size()<< std::endl; 

   return 0;

 }