/* -*- 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;

}