65 lines
2.4 KiB
C++
65 lines
2.4 KiB
C++
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//-----------------------------------------------------------------------------------
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// Implementation of a MPS algorithm via PC-tree.
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//-----------------------------------------------------------------------------------
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#include "mps.h"
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//-----------------------------------------------------------------------------------
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// Finding MPS
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//-----------------------------------------------------------------------------------
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void find_mps(ifstream* in, ofstream* out) {
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maximal_planar_subgraph_finder m;
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m.find_mps(in, out);
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}
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void maximal_planar_subgraph_finder::find_mps(ifstream* in, ofstream* out) {
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read_from_file(in);
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postOrderTraversal();
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sort_adj_list();
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determine_edges();
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back_edge_traversal();
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output(out);
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}
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//-----------------------------------------------------------------------------------
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// Imput, output
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//-----------------------------------------------------------------------------------
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//First line: a single integer indicates the number of nodes.
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//The rest: a pair of integers (i, j) represents an edge (i, j)
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//0 <= i, j < n-1, where n is number of nodes.
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void maximal_planar_subgraph_finder::read_from_file(ifstream* in) {
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int node_num, n1, n2;
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//Number of nodes.
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(*in) >> node_num;
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//initialize all the nodes.
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for (int i = 0; i < node_num; ++i) {
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_node_list.push_back(new node(P_NODE));
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_node_list[i]->set_id(i);
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}
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//Set the adj-list.
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while ((*in) >> n1 >> n2) {
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_node_list[n1]->add_adj(_node_list[n2]);
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_node_list[n2]->add_adj(_node_list[n1]);
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}
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}
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//Output a maximal planar subgraph in the same format as input.
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void maximal_planar_subgraph_finder::output(ofstream* out) {
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(*out) << _node_list.size() << endl;
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for (int i = 0; i < _edge_list.size(); ++i) {
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(*out) << _edge_list[i].first->node_id() << " " << _edge_list[i].second->node_id() << endl;
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}
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for (int i = 0; i < _back_edge_list.size(); ++i) {
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if (_is_back_edge_eliminate[i]) continue;
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(*out) << _back_edge_list[i].first->node_id() << " " << _back_edge_list[i].second->node_id() << endl;
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}
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}
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void maximal_planar_subgraph_finder::output_deleted_edges(ofstream* out) {
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(*out) << _node_list.size() << endl;
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for (int i = 0; i < _back_edge_list.size(); ++i) {
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if (!_is_back_edge_eliminate[i]) continue;
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(*out) << _back_edge_list[i].first->node_id() << " " << _back_edge_list[i].second->node_id() << endl;
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}
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}
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