f4c3@1031: #ifndef LEMON_GREEDY_TSP_H
f4c3@1031: #define LEMON_GREEDY_TSP_H
f4c3@1031: 
f4c3@1031: #include <lemon/path.h>
f4c3@1031: #include <lemon/full_graph.h>
f4c3@1031: #include <lemon/unionfind.h>
f4c3@1031: #include <algorithm>
f4c3@1031: 
f4c3@1031: namespace lemon {
f4c3@1031: 
f4c3@1031:   namespace greedy_tsp_helper {
f4c3@1031: 
f4c3@1031:     template <typename CostMap>
f4c3@1031:     class KeyComp {
f4c3@1031:       typedef typename CostMap::Key Key;
f4c3@1031:       const CostMap &cost;
f4c3@1031:       
f4c3@1031:       public:
f4c3@1031:         KeyComp(const CostMap &_cost) : cost(_cost) {}
f4c3@1031:       
f4c3@1031:         bool operator() (const Key &a, const Key &b) const {
f4c3@1031:           return cost[a] < cost[b];
f4c3@1031:         }
f4c3@1031:     };
f4c3@1031: 
f4c3@1031:   
f4c3@1031:     template <class L>
f4c3@1031:     L vectorConvert(const std::vector<FullGraph::Node> &_path) {
f4c3@1031:       return L(_path.begin(), _path.end());
f4c3@1031:     }
f4c3@1031:   
f4c3@1031:     template <>
f4c3@1031:     std::vector<FullGraph::Node> vectorConvert(const std::vector<FullGraph::Node> &_path) {
f4c3@1031:       return _path;
f4c3@1031:     }
f4c3@1031:     
f4c3@1031:   }
f4c3@1031: 
f4c3@1031: 
f4c3@1031:   template <typename CM>
f4c3@1031:   class GreedyTsp {
f4c3@1031:     private:
f4c3@1031:       GRAPH_TYPEDEFS(FullGraph);
f4c3@1031:     
f4c3@1031:     public:
f4c3@1031:       typedef CM CostMap;
f4c3@1031:       typedef typename CM::Value Cost;
f4c3@1031:       
f4c3@1031:       GreedyTsp(const FullGraph &gr, const CostMap &cost) : _gr(gr), _cost(cost) {}  
f4c3@1031: 
f4c3@1031:       Cost run() {
f4c3@1031:         typedef UnionFind<FullGraph::NodeMap<int> > Union;
f4c3@1031:         _nodes.clear();
f4c3@1031:         
f4c3@1031:         std::vector<int> path;
f4c3@1031:         path.resize(_gr.nodeNum()*2, -1);
f4c3@1031:         
f4c3@1031:         std::vector<typename CostMap::Key> sorted_edges;
f4c3@1031:         sorted_edges.reserve(_gr.edgeNum());
f4c3@1031:         for (EdgeIt n(_gr); n != INVALID; ++n)
f4c3@1031:           sorted_edges.push_back(n);
f4c3@1031: 
f4c3@1031:         std::sort(sorted_edges.begin(), sorted_edges.end(), greedy_tsp_helper::KeyComp<CostMap>(_cost));
f4c3@1031: 
f4c3@1031:         FullGraph::NodeMap<int> nodemap(_gr);
f4c3@1031:         Union unionfind(nodemap);
f4c3@1031: 
f4c3@1031:         for (NodeIt n(_gr); n != INVALID; ++n)
f4c3@1031:           unionfind.insert(n);
f4c3@1031:         
f4c3@1031:         FullGraph::NodeMap<int> degree(_gr, 0);
f4c3@1031: 
f4c3@1031:         int nodesNum = 0, i = 0;
f4c3@1031: 
f4c3@1031:         while ( nodesNum != _gr.nodeNum()-1 ) {
f4c3@1031:           const Edge &e = sorted_edges[i];
f4c3@1031:           
f4c3@1031:           const Node u = _gr.u(e),
f4c3@1031:                      v = _gr.v(e);
f4c3@1031:           
f4c3@1031:           if (degree[u]<=1 && degree[v]<=1) {
f4c3@1031:             if (unionfind.join(u, v)) {
f4c3@1031:               ++degree[u];
f4c3@1031:               ++degree[v];
f4c3@1031:               ++nodesNum;
f4c3@1031:               
f4c3@1031:               const int uid = _gr.id(u),
f4c3@1031:                         vid = _gr.id(v);
f4c3@1031:               
f4c3@1031:               
f4c3@1031:               path[uid*2 + (path[uid*2]==-1 ? 0 : 1)] = vid;
f4c3@1031:               path[vid*2 + (path[vid*2]==-1 ? 0 : 1)] = uid;
f4c3@1031:             }
f4c3@1031:           }
f4c3@1031: 
f4c3@1031:           ++i;
f4c3@1031:         }
f4c3@1031: 
f4c3@1031: 
f4c3@1031:         for (int i=0, n=-1; i<_gr.nodeNum()*2; ++i) {
f4c3@1031:           if (path[i] == -1) {
f4c3@1031:             if (n==-1) {
f4c3@1031:               n = i;
f4c3@1031:             } else {
f4c3@1031:               path[n] = i/2;
f4c3@1031:               path[i] = n/2;
f4c3@1031:               break;
f4c3@1031:             }
f4c3@1031:           }
f4c3@1031:         }
f4c3@1031: 
f4c3@1031: 
f4c3@1031:         for (int i=0, j=0, last=-1; i!=_gr.nodeNum(); ++i) {
f4c3@1031:           _nodes.push_back(_gr.nodeFromId(j));
f4c3@1031:           
f4c3@1031:           if (path[2*j] != last) {
f4c3@1031:             last = j;
f4c3@1031:             j = path[2*j];
f4c3@1031:           } else {
f4c3@1031:             last = j;
f4c3@1031:             j = path[2*j+1];
f4c3@1031:           }
f4c3@1031:         }
f4c3@1031: 
f4c3@1031:         _sum = _cost[_gr.edge(_nodes.back(), _nodes.front())];
f4c3@1031:         for (unsigned int i=0; i<_nodes.size()-1; ++i)
f4c3@1031:           _sum += _cost[_gr.edge(_nodes[i], _nodes[i+1])];
f4c3@1031: 
f4c3@1031:         return _sum;
f4c3@1031:       }
f4c3@1031: 
f4c3@1031: 
f4c3@1031: 
f4c3@1031:       template <typename L>
f4c3@1031:       void tourNodes(L &container) {
f4c3@1031:         container(greedy_tsp_helper::vectorConvert<L>(_nodes));
f4c3@1031:       }
f4c3@1031:       
f4c3@1031:       template <template <typename> class L>
f4c3@1031:       L<Node> tourNodes() {
f4c3@1031:         return greedy_tsp_helper::vectorConvert<L<Node> >(_nodes);
f4c3@1031:       }
f4c3@1031:       
f4c3@1031:       const std::vector<Node>& tourNodes() {
f4c3@1031:         return _nodes;
f4c3@1031:       }
f4c3@1031:       
f4c3@1031:       Path<FullGraph> tour() {
f4c3@1031:         Path<FullGraph> p;
f4c3@1031:         if (_nodes.size()<2)
f4c3@1031:           return p;
f4c3@1031:         
f4c3@1031:         for (unsigned int i=0; i<_nodes.size()-1; ++i) {
f4c3@1031:           p.addBack(_gr.arc(_nodes[i], _nodes[i+1]));
f4c3@1031:         }
f4c3@1031:         
f4c3@1031:         p.addBack(_gr.arc(_nodes.back(), _nodes.front()));
f4c3@1031:         
f4c3@1031:         return p;
f4c3@1031:       }
f4c3@1031:       
f4c3@1031:       Cost tourCost() {
f4c3@1031:         return _sum;
f4c3@1031:       }
f4c3@1031:       
f4c3@1031: 
f4c3@1031:     private:
f4c3@1031:       const FullGraph &_gr;
f4c3@1031:       const CostMap &_cost;
f4c3@1031:       Cost _sum;
f4c3@1031:       std::vector<Node> _nodes;
f4c3@1031:   };
f4c3@1031: 
f4c3@1031: }; // namespace lemon
f4c3@1031: 
f4c3@1031: #endif