zsuzska@1578: /* -*- C++ -*-
zsuzska@1578:  * demo/kruskal_demo.cc - Part of LEMON, a generic C++ optimization library
zsuzska@1578:  *
zsuzska@1578:  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
zsuzska@1578:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
zsuzska@1578:  *
zsuzska@1578:  * Permission to use, modify and distribute this software is granted
zsuzska@1578:  * provided that this copyright notice appears in all copies. For
zsuzska@1578:  * precise terms see the accompanying LICENSE file.
zsuzska@1578:  *
zsuzska@1578:  * This software is provided "AS IS" with no warranty of any kind,
zsuzska@1578:  * express or implied, and with no claim as to its suitability for any
zsuzska@1578:  * purpose.
zsuzska@1578:  *
zsuzska@1578:  */
zsuzska@1578: 
zsuzska@1578: ///\ingroup demos
zsuzska@1578: ///\file
zsuzska@1578: ///\brief Minimum weight spanning tree by Kruskal algorithm (demo).
zsuzska@1578: ///
athos@1583: /// This demo program shows how to find a minimum weight spanning tree
athos@1583: /// in a graph by using the Kruskal algorithm. 
alpar@1641: ///
alpar@1641: /// \include kruskal_demo.cc
zsuzska@1578: 
athos@1182: #include <iostream>
athos@1182: #include <vector>
athos@1182: 
athos@1182: #include <lemon/maps.h>
athos@1182: #include <lemon/kruskal.h>
athos@1182: #include <lemon/list_graph.h>
athos@1182: 
athos@1182: 
athos@1182: using namespace std;
athos@1182: using namespace lemon;
athos@1182: 
athos@1182: 
athos@1182: int main() {
athos@1182: 
athos@1182:   typedef ListGraph::Node Node;
athos@1182:   typedef ListGraph::Edge Edge;
athos@1182:   typedef ListGraph::NodeIt NodeIt;
athos@1182:   typedef ListGraph::EdgeIt EdgeIt;
athos@1182: 
zsuzska@1578:   ListGraph g;
zsuzska@1578:   //Make an example graph g.
zsuzska@1578:   Node s=g.addNode();
zsuzska@1578:   Node v1=g.addNode();
zsuzska@1578:   Node v2=g.addNode();
zsuzska@1578:   Node v3=g.addNode();
zsuzska@1578:   Node v4=g.addNode();
zsuzska@1578:   Node t=g.addNode();
zsuzska@1578:   
zsuzska@1578:   Edge e1 = g.addEdge(s, v1);
zsuzska@1578:   Edge e2 = g.addEdge(s, v2);
zsuzska@1578:   Edge e3 = g.addEdge(v1, v2);
zsuzska@1578:   Edge e4 = g.addEdge(v2, v1);
zsuzska@1578:   Edge e5 = g.addEdge(v1, v3);
zsuzska@1578:   Edge e6 = g.addEdge(v3, v2);
zsuzska@1578:   Edge e7 = g.addEdge(v2, v4);
zsuzska@1578:   Edge e8 = g.addEdge(v4, v3);
zsuzska@1578:   Edge e9 = g.addEdge(v3, t);
zsuzska@1578:   Edge e10 = g.addEdge(v4, t);
athos@1182: 
zsuzska@1584:   //Make the input for the kruskal.
athos@1182:   typedef ListGraph::EdgeMap<int> ECostMap;
zsuzska@1584:   ECostMap edge_cost_map(g);
zsuzska@1584: 
zsuzska@1584:   // Fill the edge_cost_map. 
zsuzska@1584:   edge_cost_map.set(e1, -10);
zsuzska@1584:   edge_cost_map.set(e2, -9);
zsuzska@1584:   edge_cost_map.set(e3, -8);
zsuzska@1584:   edge_cost_map.set(e4, -7);
zsuzska@1584:   edge_cost_map.set(e5, -6);
zsuzska@1584:   edge_cost_map.set(e6, -5);
zsuzska@1584:   edge_cost_map.set(e7, -4);
zsuzska@1584:   edge_cost_map.set(e8, -3);
zsuzska@1584:   edge_cost_map.set(e9, -2);
zsuzska@1584:   edge_cost_map.set(e10, -1);
zsuzska@1584: 
zsuzska@1584:   // Make the map or the vector, which will contain the edges of the minimum
zsuzska@1584:   // spanning tree.
zsuzska@1584: 
athos@1182:   typedef ListGraph::EdgeMap<bool> EBoolMap;
zsuzska@1578:   EBoolMap tree_map(g);
athos@1182: 
athos@1182:   vector<Edge> tree_edge_vec;
athos@1182: 
athos@1182: 
zsuzska@1584:   //Kruskal Algorithm.  
athos@1182: 
zsuzska@1584:   //Input: a graph (g); a costmap of the graph (edge_cost_map); a
zsuzska@1584:   //boolmap (tree_map) or a vector (tree_edge_vec) to store the edges
zsuzska@1584:   //of the output tree;
athos@1182: 
zsuzska@1584:   //Output: it gives back the value of the minimum spanning tree, and
zsuzska@1584:   //set true for the edges of the tree in the edgemap tree_map or
zsuzska@1584:   //store the edges of the tree in the vector tree_edge_vec;
zsuzska@1584: 
zsuzska@1584: 
zsuzska@1584:   // Kruskal with boolmap;
zsuzska@1584:   std::cout << "The weight of the minimum spanning tree is " << 
zsuzska@1584:     kruskal(g, edge_cost_map, tree_map)<<std::endl;
zsuzska@1584: 
zsuzska@1584:   int k=0;
zsuzska@1584:   std::cout << "The edges of the tree:" ;
zsuzska@1584:   for(EdgeIt i(g); i!=INVALID; ++i){
zsuzska@1584: 
zsuzska@1584:     if (tree_map[i]) { 
zsuzska@1584:       std::cout << g.id(i) <<";";
zsuzska@1584:       ++k;
zsuzska@1584:     }
zsuzska@1584:   }
zsuzska@1584:   std::cout << std::endl;
zsuzska@1584:   std::cout << "The size of the tree is: "<< k << std::endl;
zsuzska@1584: 
zsuzska@1584: 
zsuzska@1584:   // Kruskal with vector;
zsuzska@1578:   std::cout << "The weight of the minimum spanning tree again is " << 
zsuzska@1584:     kruskal(g, edge_cost_map, std::back_inserter(tree_edge_vec)) <<std::endl;
athos@1182: 
zsuzska@1578: 
zsuzska@1584: 
zsuzska@1584:   std::cout << "The edges of the tree again: " ;
zsuzska@1584:   for(int i=tree_edge_vec.size()-1; i>=0;  i--)
zsuzska@1584:     std::cout << g.id(tree_edge_vec[i]) << ";" ;
zsuzska@1584:   std::cout << std::endl;
alpar@1641:   std::cout << "The size of the tree again is: "<< tree_edge_vec.size()
alpar@1641: 	    << std::endl; 
zsuzska@1584: 
zsuzska@1584:   
athos@1182:   return 0;
athos@1182: }