Feat: deferred planarity test implementation from
https://code.google.com/archive/p/planarity-algorithms/
This commit is contained in:
commit
7f277b1768
GPG Key ID:
5BD36BA2E9EE33D0
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.vscode
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deferred_planarity_test/bin
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//-----------------------------------------------------------------------------------
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// A simple code that test the MPS algorighm.
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//-----------------------------------------------------------------------------------
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#include <iostream>
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#include <fstream>
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#include <cstdlib>
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#include <climits>
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#include "mps.h"
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using namespace std;
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void find_mps(ifstream*, ofstream*);
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//n nodes, with the probability of existence of each edge being p.
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void random_graph_generator(int n, double p, ofstream* out) {
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(*out) << n << endl;
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for (int i = 0; i < n; ++i) {
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for (int j = i+1; j < n; ++j) {
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if ((double)rand()/RAND_MAX <= p) (*out) << i << " " << j << endl;
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}
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}
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}
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//Complete graph K_n.
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void complete_graph_generator(int n, ofstream* out) {
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(*out) << n << endl;
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for (int i = 0; i < n; ++i) {
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for (int j = i+1; j < n; ++j) {
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(*out) << i << " " << j << endl;
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}
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}
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}
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//-----------------------------------------------------------------------------------
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// Main function.
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//-----------------------------------------------------------------------------------
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int main(int argc, char* argv[]) {
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if (argc == 1) {
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cout << "Usages:" << endl;
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cout << "======================" << endl;
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cout << "mps_testing -mps <infile> <outfile>" << endl;
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cout << " Process the infile, and output the resulting maximal" << endl
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<< " planar subgraph in the outfile." << endl;
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cout << "mps_testing -gen <infile> <outfile>" << endl;
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cout << " Generate a random graph as the spec given in the infile." << endl;
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while (true) {
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int x = 0;
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cin >> x;
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}
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}
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ifstream in;
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in.open(argv[2]);
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ofstream out;
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out.open(argv[3]);
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if (!in.is_open() || !out.is_open()) {
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cout << "An error occurs when opening file." << endl;
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return 0;
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}
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if (argv[1][1] == 'm') find_mps(&in, &out);
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else if (argv[1][1] == 'g') {
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int n;
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double p;
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in >> n;
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in >> p;
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random_graph_generator(n, p, &out);
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}
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return 0;
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}
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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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//Empty constructor
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maximal_planar_subgraph_finder::maximal_planar_subgraph_finder() {}
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//Destructor
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maximal_planar_subgraph_finder::~maximal_planar_subgraph_finder() {
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for (int i = 0; i < _node_list.size(); ++i) delete _node_list[i];
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for (int i = 0; i < _new_node_list.size(); ++i) delete _new_node_list[i];
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}
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node*
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maximal_planar_subgraph_finder::get_new_node(node_type t) {
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_new_node_list.push_back(new node(t));
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return _new_node_list[_new_node_list.size()-1];
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}
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//Determine the post-order-list by a DFS-traversal.
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void
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maximal_planar_subgraph_finder::postOrderTraversal() {
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node::init_mark();
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int postOrderID = 0;
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for (int i = 0; i < _node_list.size(); ++i) {
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if (!_node_list[i]->is_marked()) {
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_node_list[i]->DFS_visit(_post_order_list, postOrderID);
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}
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}
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}
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//Sort the adj-list of every node increasingly according to post-order-index.
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void
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maximal_planar_subgraph_finder::sort_adj_list() {
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vector<vector<node*> > vecList;
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vecList.resize(_post_order_list.size());
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for (int i = 0; i < _post_order_list.size(); ++i) {
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for (int j = 0; j < _post_order_list[i]->degree(); ++j) {
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vecList[_post_order_list[i]->adj(j)->post_order_index()].push_back(_post_order_list[i]);
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}
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}
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for (int i = 0; i < _post_order_list.size(); ++i) {
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_post_order_list[i]->set_adj_list(vecList[i]);
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}
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}
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//Determine edge-list, and back-edge-list.
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//Order the edges properly.
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void
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maximal_planar_subgraph_finder::determine_edges() {
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for (int i = 0; i < _post_order_list.size(); ++i) {
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if (_post_order_list[i]->parent() == 0) continue;
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_post_order_list[i]->set_1st_label(_post_order_list[i]->parent()->post_order_index());
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_edge_list.push_back(pair<node*, node*> (_post_order_list[i]->parent(), _post_order_list[i]));
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}
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for (int i = 0; i < _post_order_list.size(); ++i) {
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for (int j = 0; j < _post_order_list[i]->degree(); ++j) {
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if (_post_order_list[i]->adj(j)->post_order_index() > i) break;
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if (_post_order_list[i]->adj(j)->get_1st_label() == i) continue;
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_back_edge_list.push_back(pair<node*, node*> (_post_order_list[i], _post_order_list[i]->adj(j)));
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_is_back_edge_eliminate.push_back(false);
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}
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}
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for (int i = 0; i < _post_order_list.size(); ++i) {
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_post_order_list[i]->set_1st_label(INT_MAX);
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}
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}
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//The main part of the whole algorithm: Back-edge-traversal
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void
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maximal_planar_subgraph_finder::back_edge_traversal() {
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node* i_node = 0;
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node* current_node = 0;
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for (int i = 0; i < _back_edge_list.size(); ++i) {
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current_node = _back_edge_list[i].second;
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i_node = _back_edge_list[i].first;
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if (!back_edge_traversal(current_node, i_node->post_order_index())) _is_back_edge_eliminate[i] = true;
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}
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}
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//sub-function for the for-loop of back_edge_traversal().
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bool maximal_planar_subgraph_finder::back_edge_traversal(node* traverse_node, int index) {
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node* parent_node; //The next node to traverse.
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//If the node has been deleted.
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if (traverse_node == 0 || traverse_node->get_2nd_label() == DELETED) {
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return false;
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}
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//We have reached the i-node, stop.
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if (traverse_node->post_order_index() == index) {
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return true;
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}
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//Case 1
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if (traverse_node->get_2nd_label() == NOT_VISITED) {
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//1.1
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if (traverse_node->get_1st_label() == INT_MAX) {
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traverse_node->set_1st_label(index);
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parent_node = traverse_node->parent();
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}
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//1.2
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else if (traverse_node->get_1st_label() == index) {
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return true;
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}
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//1.3
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else if (traverse_node->get_1st_label() < index) {
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parent_node = construct(traverse_node);
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traverse_node->set_1st_label(index);
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}
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}
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//Case 2: Find the top-tier c-node.
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else {
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node* my_c_node = find(traverse_node);
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make_essential(traverse_node, my_c_node);
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//2.1
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if (my_c_node->get_1st_label() == index) {
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parent_node = my_c_node;
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}
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//2.2
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else if (my_c_node->get_1st_label() < index) {
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node* my_c_node_2 = construct(my_c_node, traverse_node);
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parent_node = my_c_node_2;
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}
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traverse_node->set_1st_label(index);
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traverse_node->set_2nd_label(NOT_VISITED);
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}
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if (back_edge_traversal(parent_node, index)) {
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if (parent_node != _post_order_list[index]) parent_node->add_child(traverse_node);
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return true;
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}
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else {
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eliminate(traverse_node);
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return false;
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}
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}
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//The p_node is originally a normal node in c_node's boundary cycle.
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//Now we transfer it to be an essential node by the following steps:
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//1. Create a replica-node of p_node to be representative of p_node in c_node.
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//2. Take out the p_node from c_node, and then set the parent of p_node to be c_node.
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//Note: We are not adding p_node to the c_node's children-list.
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void
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maximal_planar_subgraph_finder::make_essential(node* p_node, node* c_node) {
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node* sentinel = get_new_node(REPLICA_NODE);
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node* n0 = p_node->neighbor(0);
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node* n1 = p_node->neighbor(1);
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sentinel->init_replica(p_node, c_node);
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c_node->add_essential(sentinel);
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sentinel->set_to_boundary_path(n0, n1);
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sentinel->inherit_AE(p_node);
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n0->set_neighbor(n0->get_next(p_node), sentinel);
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n1->set_neighbor(n1->get_next(p_node), sentinel);
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p_node->set_neighbor((node*)0, (node*)0);
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p_node->set_parent(c_node);
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}
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//Find the top-tier c-node of the input node.
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//Note: We don't set the input node to be essential node of the top-tier c-node.
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//When terminated, the input node will be in the boundary cycle of top-tier c-node.
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node* maximal_planar_subgraph_finder::find(node* n) {
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pair<pair<node*, node*>, pair<node*, node*> > boundary;
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node* c_node_new = 0;
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int c_node_size = 0;
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node* return_node = 0;
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if (n->parent() == 0) {
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//If n is already a node in boundary cycle.
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//Note: n must not be an essential node, otherwise it will never enter the function.
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//Find the first(nearest to n) essential node.
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boundary.first = parallel_search_sentinel(n, c_node_new);
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}
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else {
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//If n is not a node in boundary cycle.
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//It is in an Artificial edge.
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//Trim it.
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boundary = trim(n);
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//Find the first(nearest to n) essential node.
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boundary.first = parallel_search_sentinel(boundary.first.first, boundary.first.second, boundary.second.first, boundary.second.second, c_node_new);
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}
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//Find the c-node in the current hierachy .
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//If it is top-tier, return it.
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if (c_node_new != 0) return c_node_new;
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c_node_new = (boundary.first).first->get_c_node();
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//If not, find the two nearest essential node, eliminate the rest nodes.
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c_node_size = c_node_new->c_node_size();
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boundary.second = count_sentinel_elimination(boundary.first, c_node_size);
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//Go to the higher hierachy, and continue to find.
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if (c_node_new->get_2nd_label() == ARTIFICIAL_EDGE) {
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//A peculiar technic:
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//Remove all the children of c_node_new but the one that should remains(Let it be u).
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//Remove all other essential nodes, pretend to be a c-node of size equals 2.
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//Call find(u).
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node* u = 0;
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for (int i = 0; i < c_node_new->child_num(); ++i) {
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if (node::is_same(boundary.first.first, c_node_new->child(i)) || node::is_same(boundary.second.first, c_node_new->child(i))) {
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u = c_node_new->child(i);
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}
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else eliminate(c_node_new->child(i));
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}
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c_node_new->clear_children();
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c_node_new->add_child(u);
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c_node_new->clear_essential();
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c_node_new->add_essential(boundary.first.first);
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c_node_new->add_essential(boundary.second.first);
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return_node = find(u);
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}
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else return_node = find(c_node_new);
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//Merge the part of boundary cycle remains in current hierachy to the top-tier c-node.
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merge(boundary, c_node_new);
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return return_node;
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}
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//The list_node is a c-node.
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//The boundary indicates the part of the boundary cycle of c-node needs to be merge to the higher hierachy.
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//Replace the list_node by boundary.
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//Set list_node to be DELETED.
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//Note: We do not eliminate anything in this function.
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void
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maximal_planar_subgraph_finder::merge(pair<pair<node*, node*>, pair<node*, node*> > boundary, node* list_node) {
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node* n0 = list_node->neighbor(0);
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node* n1 = list_node->neighbor(1);
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node* s0, * s0_prev;
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node* s1, * s1_prev;
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if (node::is_same(boundary.first.first, n0)) {
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s0 = boundary.first.first;
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s0_prev = boundary.first.second;
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s1 = boundary.second.first;
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s1_prev = boundary.second.second;
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}
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else {
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s0 = boundary.second.first;
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s0_prev = boundary.second.second;
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s1 = boundary.first.first;
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s1_prev = boundary.first.second;
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}
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if (s0_prev == s1 && s1_prev == s0) {
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n0->set_neighbor(n0->get_next(list_node), n1);
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n1->set_neighbor(n1->get_next(list_node), n0);
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}
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else {
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n0->set_neighbor(n0->get_next(list_node), s0_prev);
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n1->set_neighbor(n1->get_next(list_node), s1_prev);
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s0_prev->set_neighbor(s0_prev->get_next(s0), n0);
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s1_prev->set_neighbor(s1_prev->get_next(s1), n1);
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}
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//Inherit AE.
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n0->inherit_AE(s0);
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n1->inherit_AE(s1);
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//Delete c-node
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list_node->set_2nd_label(DELETED);
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}
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//Set u and its subtree to be DELETED.
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//If u has some AE, eliminate them.
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//We don't do anything about u's parent, neighborhood.(Only children are affected.)
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//If u is a p-node, we don't eliminate anything in the lower hierachy that corresponds to the same p-node.
|
||||||
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//If u is a c-node, we eliminate all nodes in u's boundary cycle.
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void
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maximal_planar_subgraph_finder::eliminate(node* u) {
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||||||
|
if (u->get_2nd_label() == DELETED) return;
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||||||
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u->set_2nd_label(DELETED);
|
||||||
|
if (u->type() == C_NODE) {
|
||||||
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node* list_node = u->get_a_list_node();
|
||||||
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node* n0, * n0_prev;;
|
||||||
|
node* temp = 0;
|
||||||
|
n0 = list_node;
|
||||||
|
n0_prev = list_node->neighbor(0);
|
||||||
|
while (true) {
|
||||||
|
eliminate(n0);
|
||||||
|
temp = n0;
|
||||||
|
n0 = n0->get_next(n0_prev);
|
||||||
|
n0_prev = temp;
|
||||||
|
if (n0 == list_node) break;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
else if (u->type() == P_NODE) {
|
||||||
|
for (int i = 0; i < u->degree(); ++i) {
|
||||||
|
if (u->adj(i)->post_order_index() < u->post_order_index() && u->adj(i)->get_1st_label() == INT_MAX) eliminate(u->adj(i));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
if (u->AE(0) != 0) eliminate(u->AE(0));
|
||||||
|
if (u->AE(1) != 0) eliminate(u->AE(1));
|
||||||
|
for (int i = 0; i < u->child_num(); ++i) {
|
||||||
|
eliminate(u->child(i));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//Eliminate the AE of(u,v)-link that points to u.(If exists)
|
||||||
|
void
|
||||||
|
maximal_planar_subgraph_finder::eliminate_AE(node* u, node* v) {
|
||||||
|
int v_index = v->post_order_index();
|
||||||
|
if (u->AE(0) != 0 && u->AE(0)->get_1st_label() == v_index) {
|
||||||
|
eliminate (u->AE(0));
|
||||||
|
u->set_AE(0, 0);
|
||||||
|
}
|
||||||
|
if (u->AE(1) != 0 && u->AE(1)->get_1st_label() == v_index) {
|
||||||
|
eliminate (u->AE(1));
|
||||||
|
u->set_AE(1, 0);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//The input node u must not be c-node.
|
||||||
|
//The traversed node is in the AE = (up <- down).
|
||||||
|
//The returned boundary = [up, up_prev ..., down_prev, down].
|
||||||
|
//Direction: up it higher than down.
|
||||||
|
pair<pair<node*, node*>, pair<node*, node*> >
|
||||||
|
maximal_planar_subgraph_finder::trim(node* u) {
|
||||||
|
node* up = 0;
|
||||||
|
node* down = 0;
|
||||||
|
//Since we may do c-node extension in the future, we need to memorize next in order to deduce prev.
|
||||||
|
node* up_next = 0;
|
||||||
|
node* down_next = 0;
|
||||||
|
node* new_AE_root = 0;
|
||||||
|
//The index from small to large indicates the path that we traversed, note that u = node_list[0].
|
||||||
|
vector<node*> node_list;
|
||||||
|
node* curr = u;
|
||||||
|
node_list.push_back(u);
|
||||||
|
//Traverse upward.
|
||||||
|
while (true) {
|
||||||
|
curr = curr->parent();
|
||||||
|
if (curr->type() == AE_VIRTUAL_ROOT) {
|
||||||
|
up = curr->parent();
|
||||||
|
//case 1: We are in a newly created c-node.
|
||||||
|
//It has only one AE, and the two neighbor-pointer point to the same one.
|
||||||
|
if (up->neighbor(0) == up->neighbor(1)) {
|
||||||
|
down = up->neighbor(0);
|
||||||
|
up->set_neighbor(down, node_list[node_list.size()-1]);
|
||||||
|
down->set_neighbor(up, node_list[0]);
|
||||||
|
curr->remove_child(node_list[node_list.size()-1]);
|
||||||
|
//There's no other child, just delete the AE.
|
||||||
|
if (curr->child_num() == 0) {
|
||||||
|
up->set_AE(0, 0);
|
||||||
|
up->set_AE(1, 0);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
//case 2: General case.
|
||||||
|
else {
|
||||||
|
if (up->neighbor(0)->post_order_index() == curr->get_1st_label()) down = up->neighbor(0);
|
||||||
|
else down = up->neighbor(1);
|
||||||
|
up->set_neighbor(up->get_next(down), node_list[node_list.size()-1]);
|
||||||
|
down->set_neighbor(down->get_next(up), node_list[0]);
|
||||||
|
curr->remove_child(node_list[node_list.size()-1]);
|
||||||
|
eliminate_AE(up, down);
|
||||||
|
}
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
node_list.push_back(curr);
|
||||||
|
}
|
||||||
|
//Set the "downward" AE of node_list[0].
|
||||||
|
new_AE_root = get_new_node(AE_VIRTUAL_ROOT);
|
||||||
|
new_AE_root->init_AE(node_list[0]);
|
||||||
|
//Eliminate the children other than the path.
|
||||||
|
for (int i = 1; i < node_list.size(); ++i) {
|
||||||
|
for (int j = 0; j < node_list[i]->child_num(); ++j) {
|
||||||
|
if (node_list[i]->child(j) != node_list[i-1]) eliminate(node_list[i]->child(j));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
//Set to the boundary path.
|
||||||
|
if (node_list.size() == 1) node_list[0]->set_to_boundary_path(up, down);
|
||||||
|
else {
|
||||||
|
node_list[0]->set_to_boundary_path(down, node_list[1]);
|
||||||
|
node_list[node_list.size()-1]->set_to_boundary_path(up, node_list[node_list.size()-2]);
|
||||||
|
for (int i = 1; i < node_list.size()-1; ++i) {
|
||||||
|
node_list[i]->set_to_boundary_path(node_list[i-1], node_list[i+1]);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
//Set the next of up and down.
|
||||||
|
up_next = up->get_next(node_list[node_list.size()-1]);
|
||||||
|
down_next = down->get_next(node_list[0]);
|
||||||
|
//Unfold the c-nodes in the node_list.
|
||||||
|
for (int i = 0; i < node_list.size(); ++i) {
|
||||||
|
if (node_list[i]->type() == C_NODE) c_node_extension(node_list[i]);
|
||||||
|
}
|
||||||
|
//Return the new boundary.
|
||||||
|
return pair<pair<node*, node*>, pair<node*, node*> > (pair<node*, node*>(up, up->get_next(up_next)), pair<node*, node*>(down, down->get_next(down_next)));
|
||||||
|
}
|
||||||
|
|
||||||
|
//The trim's sub-function.
|
||||||
|
//The input c-node does not contain any children nor parent, but it has two neighbors, which is originally c-node's parent and one child.
|
||||||
|
//If c-node's size equals 2, then we don't need to unfold it.
|
||||||
|
//Otherwise, it must has size equals 3.
|
||||||
|
//And then we find that redundent essential node, and remove the nodes that need not remains.
|
||||||
|
//Merge the remain part to the higher hierachy.
|
||||||
|
void
|
||||||
|
maximal_planar_subgraph_finder::c_node_extension(node* c_node) {
|
||||||
|
//size == 2
|
||||||
|
if (c_node->c_node_size() == 2) return;
|
||||||
|
//size == 3
|
||||||
|
node* sentinel = 0;
|
||||||
|
for (int i = 0; i < c_node->c_node_size(); ++i) {
|
||||||
|
if (!node::is_same(c_node->essential(i), c_node->neighbor(0)) && !node::is_same(c_node->essential(i), c_node->neighbor(1))) {
|
||||||
|
sentinel = c_node->essential(i);
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
eliminate(sentinel);
|
||||||
|
//The two other essential nodes and their subsequent neighbor.
|
||||||
|
pair<node*, node*> sentinel_0;
|
||||||
|
pair<node*, node*> sentinel_1;
|
||||||
|
node* n0, * n0_prev = sentinel;
|
||||||
|
node* n1, * n1_prev = sentinel;
|
||||||
|
node* temp = 0;
|
||||||
|
n0 = sentinel->neighbor(0);
|
||||||
|
n1 = sentinel->neighbor(1);
|
||||||
|
while (true) {//Toward the direction of n0.
|
||||||
|
if (n0->is_sentinel()) {//If we meet a essential node, stop, don't remove it.
|
||||||
|
sentinel_0 = pair<node*, node*> (n0, n0->get_next(n0_prev));
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
eliminate(n0);
|
||||||
|
temp = n0;
|
||||||
|
n0 = n0->get_next(n0_prev);
|
||||||
|
n0_prev = temp;
|
||||||
|
}
|
||||||
|
while (true) {//Toward the direction of n0.
|
||||||
|
if (n1->is_sentinel()) {//If we meet a essential node, stop, don't remove it.
|
||||||
|
sentinel_1 = pair<node*, node*> (n1, n1->get_next(n1_prev));
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
eliminate(n1);
|
||||||
|
temp = n1;
|
||||||
|
n1 = n1->get_next(n1_prev);
|
||||||
|
n1_prev = temp;
|
||||||
|
}
|
||||||
|
|
||||||
|
//Remember to remove the AE toward two essential nodes that is in the delete region.
|
||||||
|
eliminate_AE(sentinel_0.first, sentinel_0.first->get_next(sentinel_0.second));
|
||||||
|
eliminate_AE(sentinel_1.first, sentinel_1.first->get_next(sentinel_1.second));
|
||||||
|
//Reset the neighborhood of two essential nodes.
|
||||||
|
sentinel_0.first->set_neighbor(sentinel_1.first, sentinel_0.second);
|
||||||
|
sentinel_1.first->set_neighbor(sentinel_0.first, sentinel_1.second);
|
||||||
|
//Merge to upper boundary cycle.
|
||||||
|
merge(pair<pair<node*, node*>, pair<node*, node*> >(sentinel_0, sentinel_1), c_node);
|
||||||
|
}
|
||||||
|
|
||||||
|
//u is a normal p-node.
|
||||||
|
//We'll do the work of elimination, and renewing of children-list.
|
||||||
|
void
|
||||||
|
maximal_planar_subgraph_finder::recursively_shaving(node* u) {
|
||||||
|
node* parent_node = 0;
|
||||||
|
node* node_x = 0;
|
||||||
|
pair<node*, node*> new_two_child;
|
||||||
|
vector<node*> new_child_list;
|
||||||
|
//p-node
|
||||||
|
if (u->type() == P_NODE) {
|
||||||
|
for (int i = 0; i < u->child_num(); ++i) recursively_shaving(u->child(i));
|
||||||
|
}
|
||||||
|
//c-node
|
||||||
|
else {
|
||||||
|
//We don't need to shave if u has only one child.
|
||||||
|
if (u->child_num() == 1) {
|
||||||
|
recursively_shaving(u->child(0));
|
||||||
|
return;
|
||||||
|
}
|
||||||
|
//More than one child.
|
||||||
|
parent_node = u->parent();
|
||||||
|
//Find node_x, and shave it.
|
||||||
|
for (int i = 0; i < u->c_node_size(); ++i) {
|
||||||
|
if (node::is_same(u->essential(i), parent_node)) {
|
||||||
|
node_x = u->essential(i);
|
||||||
|
new_two_child = shave(node_x);
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
//Reset children-list and essential node.
|
||||||
|
for (int i = 0; i < u->child_num(); ++i) {
|
||||||
|
if (node::is_same(u->child(i), new_two_child.first) || node::is_same(u->child(i), new_two_child.second)) new_child_list.push_back(u->child(i));
|
||||||
|
else eliminate(u->child(i));
|
||||||
|
}
|
||||||
|
u->clear_children();
|
||||||
|
u->clear_essential();
|
||||||
|
u->add_essential(node_x);
|
||||||
|
u->add_essential(new_two_child.first);
|
||||||
|
u->add_essential(new_two_child.second);
|
||||||
|
u->add_child(new_child_list[0]);
|
||||||
|
u->add_child(new_child_list[1]);
|
||||||
|
for (int i = 0; i < u->child_num(); ++i) recursively_shaving(u->child(i));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//In this function, we only deal with inner part of c-node.
|
||||||
|
//x,y,z are essential nodes, let y,z be x's nearest essential nodes in w's boundary cycle.
|
||||||
|
//Anything outside [x,y], and[x,z] will be eliminated.
|
||||||
|
//Definition of y_prev, z_prev: ..., y, y_prev, ..., x, ..., z_prev, z, ...
|
||||||
|
//Return pair = (y,z). Note: What we return is the replica-node in the inner part of c-node.
|
||||||
|
//The work of deleting children will be done by recursively_shaving().
|
||||||
|
pair<node*, node*>
|
||||||
|
maximal_planar_subgraph_finder::shave(node* x) {
|
||||||
|
//c-node.
|
||||||
|
node* c_node = x->get_c_node();
|
||||||
|
//No need to shave if child_num == 1.
|
||||||
|
if (c_node->child_num() == 1) return pair<node*, node*>((node*)0, (node*)0);
|
||||||
|
//sentinel_1 = (y, y_prev). Note: At this time, c-node must has type equals ARTIFICIAL_EDGE, so no problem here.
|
||||||
|
pair<node*, node*> sentinel_1 = parallel_search_sentinel(x, c_node);
|
||||||
|
//sentinel_2 = (z, z_prev). Same as above.
|
||||||
|
pair<node*, node*> sentinel_2 = count_sentinel_elimination(sentinel_1, c_node->child_num());
|
||||||
|
return pair<node*, node*>(sentinel_1.first, sentinel_2.first);
|
||||||
|
}
|
||||||
|
|
||||||
|
//Use parallel_search to find essential nodes. Return (essential nodes that we find, its prev).
|
||||||
|
//x is not in the searching region.
|
||||||
|
//If the c-node found is top-tier, then set all the nodes during searching a pointer to c-node, set c to be that c-node, and return pair be all null.
|
||||||
|
pair<node*, node*>
|
||||||
|
maximal_planar_subgraph_finder::parallel_search_sentinel(node* x, node* &c) {
|
||||||
|
node* n0, * n0_prev = x;
|
||||||
|
node* n1, * n1_prev = x;
|
||||||
|
n0 = x->neighbor(0);
|
||||||
|
n1 = x->neighbor(1);
|
||||||
|
return parallel_search_sentinel(n0, n0_prev, n1, n1_prev, c);
|
||||||
|
}
|
||||||
|
|
||||||
|
//Another version of parallel search: n0, n0_prev, ..., n1_prev, n1
|
||||||
|
//searching region = (...n0] [n1...). Find the nearest essential node.
|
||||||
|
//return (essential nodes that we find, its prev).
|
||||||
|
pair<node*, node*>
|
||||||
|
maximal_planar_subgraph_finder::parallel_search_sentinel(node* n0, node* n0_prev, node* n1, node* n1_prev, node* & c) {
|
||||||
|
node* temp = 0;
|
||||||
|
vector<node*> traversed;
|
||||||
|
while (true) {
|
||||||
|
//If c-node is top-tier.
|
||||||
|
//note: If c points to a c-node traversed in some previous iteration, then it must not be top-tier, so it'll not pass the if-condition.
|
||||||
|
if (n0->get_c_node() != 0 && n0->get_c_node()->get_2nd_label() == NOT_VISITED) {
|
||||||
|
c = n0->get_c_node();
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
if (n1->get_c_node() != 0 && n1->get_c_node()->get_2nd_label() == NOT_VISITED) {
|
||||||
|
c = n1->get_c_node();
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
//If an essential-node found.
|
||||||
|
if (n0->is_sentinel()) return pair<node*, node*>(n0, n0_prev);
|
||||||
|
if (n1->is_sentinel()) return pair<node*, node*>(n1, n1_prev);
|
||||||
|
//Just a normal node..
|
||||||
|
traversed.push_back(n0);
|
||||||
|
traversed.push_back(n1);
|
||||||
|
temp = n0;
|
||||||
|
n0 = n0->get_next(n0_prev);
|
||||||
|
n0_prev = temp;
|
||||||
|
temp = n1;
|
||||||
|
n1 = n1->get_next(n1_prev);
|
||||||
|
n1_prev = temp;
|
||||||
|
}
|
||||||
|
|
||||||
|
//If the c-node found is top-tier, then assign all the traversed node a pointer to c-node.
|
||||||
|
for (int i = 0; i < traversed.size(); ++i) traversed[i]->set_c_node(c);
|
||||||
|
return pair<node*, node*>((node*)0, (node*)0);
|
||||||
|
}
|
||||||
|
|
||||||
|
// sentinel_1= (y, y_prev)
|
||||||
|
// return pair = (z, z_prev)
|
||||||
|
// ..., y_prev, y,[ ...(contains num_sentinel-2 essential nodes)...], z, z_prev, ... : eliminate the [...] part.
|
||||||
|
// Which means, num_sentinel = Number of essential nodes in the region [y, z].
|
||||||
|
// Note: y, z(Of course, and their prev,) will not be eliminated.
|
||||||
|
// Note: All the node that correspond to the same one as deleted node in higher hierachy will not be affected.
|
||||||
|
// The boundary cycle of c-node will be re-connected, AE be properly handled.
|
||||||
|
// Do nothing outside the c-node.
|
||||||
|
pair<node*, node*> maximal_planar_subgraph_finder::count_sentinel_elimination(pair<node*, node*> sentinel_1, int num_sentinel) {
|
||||||
|
pair<node*, node*> sentinel_2; //(z, z_prev)
|
||||||
|
int count = 1;//Count the essential nodes traversed.
|
||||||
|
node* n0 = sentinel_1.first->get_next(sentinel_1.second), * n0_prev = sentinel_1.first;//Going one step further.
|
||||||
|
node* temp = 0;
|
||||||
|
while (true) {
|
||||||
|
if (n0->is_sentinel()) {
|
||||||
|
++count;//counter
|
||||||
|
if (count == num_sentinel) {//We have reached y. Note: We will not eleminate y.
|
||||||
|
sentinel_2.first = n0;
|
||||||
|
sentinel_2.second = n0->get_next(n0_prev);
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
eliminate(n0);
|
||||||
|
temp = n0;
|
||||||
|
n0 = n0->get_next(n0_prev);
|
||||||
|
n0_prev = temp;
|
||||||
|
}
|
||||||
|
//Remember to eliminate AE toward two essential nodes that is in the deleted region.
|
||||||
|
eliminate_AE(sentinel_2.first, sentinel_2.first->get_next(sentinel_2.second));
|
||||||
|
eliminate_AE(sentinel_1.first, sentinel_1.first->get_next(sentinel_1.second));
|
||||||
|
//Reset neighborhood of two essential nodes.
|
||||||
|
sentinel_2.first->set_neighbor(sentinel_1.first, sentinel_2.second);
|
||||||
|
sentinel_1.first->set_neighbor(sentinel_2.first, sentinel_1.second);
|
||||||
|
return sentinel_2;
|
||||||
|
}
|
||||||
|
|
||||||
|
//Used when u has label equals <i, 0>, i<j, where j is current iteration.
|
||||||
|
//Create a c-node with u being first essential node, and i being head. Return it.
|
||||||
|
//We'll done the parent-linke of (u -> c-node -> node_i).
|
||||||
|
//We don't create child-link here.
|
||||||
|
//Default label of newly contructed c-node is (INT_MAX, NOT_VISITED).
|
||||||
|
node*
|
||||||
|
maximal_planar_subgraph_finder::construct(node* u) {
|
||||||
|
//Basic works.
|
||||||
|
int i_label = u->get_1st_label();
|
||||||
|
node* node_i = _post_order_list[u->get_1st_label()];
|
||||||
|
parenting_labeling_shaving(u, node_i);
|
||||||
|
|
||||||
|
//Get some new nodes.
|
||||||
|
node* i_sentinel = get_new_node(REPLICA_NODE);
|
||||||
|
node* u_sentinel = get_new_node(REPLICA_NODE);
|
||||||
|
node* new_c_node = get_new_node(C_NODE);
|
||||||
|
node* new_AE_root = get_new_node(AE_VIRTUAL_ROOT);
|
||||||
|
|
||||||
|
//Setting of replica-nodes.
|
||||||
|
i_sentinel->init_replica(node_i, new_c_node);
|
||||||
|
u_sentinel->init_replica(u, new_c_node);
|
||||||
|
for (int i = 0; i < u->child_num(); ++i) {
|
||||||
|
u_sentinel->add_child(u->child(i));
|
||||||
|
}
|
||||||
|
new_AE_root->init_AE(u_sentinel);
|
||||||
|
|
||||||
|
//Neighborhood setting of replica-nodes in c-node.
|
||||||
|
i_sentinel->set_to_boundary_path(u_sentinel, u_sentinel);
|
||||||
|
u_sentinel->set_to_boundary_path(i_sentinel, i_sentinel);
|
||||||
|
|
||||||
|
//Default label of c-node.
|
||||||
|
new_c_node->set_1st_label(INT_MAX);
|
||||||
|
new_c_node->set_2nd_label(NOT_VISITED);
|
||||||
|
|
||||||
|
//Set essential node of c-node.
|
||||||
|
new_c_node->add_essential(i_sentinel);
|
||||||
|
new_c_node->add_essential(u_sentinel);
|
||||||
|
|
||||||
|
//Parenting
|
||||||
|
new_c_node->set_parent(node_i);
|
||||||
|
u->set_parent(new_c_node);
|
||||||
|
|
||||||
|
//Clear children-list of u_node. (which has benn transfered to AE inside c-node.)
|
||||||
|
u->clear_children();
|
||||||
|
|
||||||
|
return new_c_node;
|
||||||
|
}
|
||||||
|
|
||||||
|
//The case when the first explored node is c-node (The input parameter c).
|
||||||
|
//The p-node that trigger c(The input parameter p), has p->c parent-link already, and p is essential(not essential before triggered).
|
||||||
|
//But we don't have c->p child-link yet.
|
||||||
|
//We are not going to establish that child-link in this function. (Will be done in BET's main loop.)
|
||||||
|
//Set c to be DELETED.
|
||||||
|
node*
|
||||||
|
maximal_planar_subgraph_finder::construct(node* c, node* p) {
|
||||||
|
//Basic works.
|
||||||
|
int i_label = c->get_1st_label();
|
||||||
|
node* node_i = _post_order_list[c->get_1st_label()];
|
||||||
|
parenting_labeling_shaving(p, node_i);
|
||||||
|
//note: Now, c must have exactly two children left, and c has a parent-link to p, p has achild link to c, too.
|
||||||
|
//Remember to handle them later.
|
||||||
|
|
||||||
|
//Get some new nodes.
|
||||||
|
node* i_sentinel = get_new_node(REPLICA_NODE);
|
||||||
|
node* new_c_node = get_new_node(C_NODE);
|
||||||
|
i_sentinel->init_replica(node_i, new_c_node);
|
||||||
|
|
||||||
|
//Strategy: Build thisboundary cycle first: (i, child(0), c, child(1), i).
|
||||||
|
//And then find the two replica-node corresponding to the two children in c, and merge.
|
||||||
|
node* ch0 = c->child(0);
|
||||||
|
node* ch1 = c->child(1);
|
||||||
|
node* AE_root_0 = get_new_node(AE_VIRTUAL_ROOT);
|
||||||
|
node* AE_root_1 = get_new_node(AE_VIRTUAL_ROOT);
|
||||||
|
AE_root_0->init_AE(ch0);
|
||||||
|
AE_root_1->init_AE(ch1);
|
||||||
|
i_sentinel->set_to_boundary_path(ch0, ch1);
|
||||||
|
ch0->set_to_boundary_path(i_sentinel, c);
|
||||||
|
ch1->set_to_boundary_path(i_sentinel, c);
|
||||||
|
c->set_to_boundary_path(ch0, ch1);
|
||||||
|
|
||||||
|
//find the boundary in c, merge!
|
||||||
|
node* sent_0;
|
||||||
|
node* sent_1;
|
||||||
|
node* sent_p;
|
||||||
|
for (int i = 0; i < c->c_node_size(); ++i) {
|
||||||
|
if (node::is_same(c->essential(i), ch0)) sent_0 = c->essential(i);
|
||||||
|
else if (node::is_same(c->essential(i), ch1)) sent_1 = c->essential(i);
|
||||||
|
else if (node::is_same(c->essential(i), p)) sent_p = c->essential(i);
|
||||||
|
}
|
||||||
|
merge(pair<pair<node*, node*>, pair<node*, node*> > (pair<node*, node*>(sent_0, sent_0->get_next(sent_1)), pair<node*, node*>(sent_1, sent_1->get_next(sent_0))), c);
|
||||||
|
|
||||||
|
//Set essential-node of c-node.
|
||||||
|
new_c_node->add_essential(i_sentinel);
|
||||||
|
new_c_node->add_essential(sent_p);
|
||||||
|
|
||||||
|
//Default label of c-node.
|
||||||
|
new_c_node->set_1st_label(INT_MAX);
|
||||||
|
new_c_node->set_2nd_label(NOT_VISITED);
|
||||||
|
|
||||||
|
//Parenting.
|
||||||
|
new_c_node->set_parent(node_i);
|
||||||
|
|
||||||
|
//p-node, p_sent.
|
||||||
|
sent_p->set_c_node(new_c_node);
|
||||||
|
p->clear_children();
|
||||||
|
p->set_parent(new_c_node);
|
||||||
|
|
||||||
|
//Delete c-node
|
||||||
|
c->set_2nd_label(DELETED);
|
||||||
|
|
||||||
|
return new_c_node;
|
||||||
|
}
|
||||||
|
|
||||||
|
//Some basic works in constructing c-node.
|
||||||
|
//u is the first explored node in the newly constructed c-node.
|
||||||
|
//In the case of newly constructed c-node itself is c-node, u will be the p-node that trigger the c-node.
|
||||||
|
//And in this case, p->c parent-link has been established, but c->p child-link not.
|
||||||
|
void
|
||||||
|
maximal_planar_subgraph_finder::parenting_labeling_shaving(node* u, node* node_i) {
|
||||||
|
//reverse parent-children relation in [u, node_i] as following.
|
||||||
|
//(u-> ... ->y->i) -> (u<- ... <-y , i).
|
||||||
|
vector<node*> u_i_path;
|
||||||
|
u_i_path.push_back(u);
|
||||||
|
while (true) {
|
||||||
|
u_i_path.push_back(u_i_path[u_i_path.size()-1]->parent());
|
||||||
|
if (u_i_path[u_i_path.size()-1] == node_i) break;
|
||||||
|
}
|
||||||
|
for (int i = 0; i < u_i_path.size()-2; ++i) {
|
||||||
|
u_i_path[i]->add_child(u_i_path[i+1]);
|
||||||
|
u_i_path[i+1]->set_parent(u_i_path[i]);
|
||||||
|
}
|
||||||
|
for (int i = 0; i < u_i_path.size()-2; ++i) {
|
||||||
|
for (int j = 0; j < u_i_path[i+1]->child_num(); ++j) {
|
||||||
|
if (u_i_path[i+1]->child(j) == u_i_path[i]) {
|
||||||
|
u_i_path[i+1]->remove_child(j);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
u_i_path[0]->set_parent(0);
|
||||||
|
|
||||||
|
//BFS-traversal, all labeled to <i,1>, and then shave the c-node.
|
||||||
|
u->recursively_labeling();
|
||||||
|
recursively_shaving(u);
|
||||||
|
}
|
||||||
|
|
@ -0,0 +1,179 @@
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// Header for modules: mps.cpp, mps_test.cpp, node.cpp.
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
#ifndef _MPS_H
|
||||||
|
#define _MPS_H
|
||||||
|
|
||||||
|
#include <iostream>
|
||||||
|
#include <fstream>
|
||||||
|
#include <vector>
|
||||||
|
#include <utility>
|
||||||
|
#include <climits>
|
||||||
|
|
||||||
|
using namespace std;
|
||||||
|
|
||||||
|
class node;
|
||||||
|
class maximal_planar_subgraph_finder;
|
||||||
|
|
||||||
|
enum label {
|
||||||
|
NOT_VISITED = 0,
|
||||||
|
ARTIFICIAL_EDGE = 1,
|
||||||
|
BOUNDARY_PATH = 2,
|
||||||
|
DELETED = 3
|
||||||
|
};
|
||||||
|
|
||||||
|
enum node_type {
|
||||||
|
P_NODE = 0,
|
||||||
|
C_NODE = 1,
|
||||||
|
REPLICA_NODE = 2,
|
||||||
|
AE_VIRTUAL_ROOT = 3
|
||||||
|
};
|
||||||
|
|
||||||
|
class node
|
||||||
|
{
|
||||||
|
public:
|
||||||
|
//CONSTRUCTOR
|
||||||
|
node(node_type t);
|
||||||
|
|
||||||
|
//DESTRUCTOR
|
||||||
|
~node() {}
|
||||||
|
|
||||||
|
//TYPE, ID, INDEX
|
||||||
|
node_type type();
|
||||||
|
int post_order_index();
|
||||||
|
void set_id(int i);
|
||||||
|
void set_post_order_index(int i);
|
||||||
|
void recursively_labeling();
|
||||||
|
int node_id();
|
||||||
|
|
||||||
|
//DFS-TREE
|
||||||
|
void add_adj(node* n);
|
||||||
|
int degree();
|
||||||
|
node* adj(int i);
|
||||||
|
void set_adj_list(vector<node*> vec);
|
||||||
|
void DFS_visit(vector<node*> &dfsList, int &index);
|
||||||
|
|
||||||
|
//PARENT-CHILDREN
|
||||||
|
void set_parent(node* n) ;
|
||||||
|
node* parent();
|
||||||
|
int child_num();
|
||||||
|
node* child(int i);
|
||||||
|
void add_child(node* n);
|
||||||
|
void clear_children();
|
||||||
|
void remove_child(int i);
|
||||||
|
void remove_child(node* n);
|
||||||
|
vector<node*>* get_children_list();
|
||||||
|
|
||||||
|
//BOUNDARY_PATH
|
||||||
|
void set_to_boundary_path(node* n0, node* n1);
|
||||||
|
void set_neighbor(int i, node* n);
|
||||||
|
void set_neighbor(node* u, node* v);
|
||||||
|
node* neighbor(int i);
|
||||||
|
node* get_next(node* prev);
|
||||||
|
|
||||||
|
//ARTIFICIAL EDGE
|
||||||
|
node* AE(int i);
|
||||||
|
void set_AE(int i, node* j);
|
||||||
|
void add_AE(node* j);
|
||||||
|
void inherit_AE(node* u);
|
||||||
|
void init_AE(node* u);
|
||||||
|
|
||||||
|
//REPLICA
|
||||||
|
node* original_node();
|
||||||
|
node* get_c_node();
|
||||||
|
void set_c_node(node* c);
|
||||||
|
bool is_sentinel();
|
||||||
|
static bool is_same(node* n1, node* n2);
|
||||||
|
void init_replica(node* u, node* c);
|
||||||
|
|
||||||
|
//LABELING
|
||||||
|
void set_1st_label(int i);
|
||||||
|
void set_2nd_label(label i);
|
||||||
|
int get_1st_label();
|
||||||
|
label get_2nd_label();
|
||||||
|
|
||||||
|
//C-NODE
|
||||||
|
node* get_a_list_node();
|
||||||
|
int c_node_size();
|
||||||
|
node* essential(int i);
|
||||||
|
void clear_essential();
|
||||||
|
void add_essential(node* u);
|
||||||
|
|
||||||
|
//MARK
|
||||||
|
void mark();
|
||||||
|
static void init_mark();
|
||||||
|
void un_mark();
|
||||||
|
bool is_marked();
|
||||||
|
|
||||||
|
private:
|
||||||
|
//Basic information.
|
||||||
|
node_type _type;
|
||||||
|
pair<int, label> _label;
|
||||||
|
|
||||||
|
//Information about neighborhood.
|
||||||
|
node* _neighbor[2];
|
||||||
|
node* _AE_root[2];
|
||||||
|
|
||||||
|
//Information about higher hierarchy.
|
||||||
|
node* _original_node;
|
||||||
|
node* _c_node;
|
||||||
|
|
||||||
|
//Information about parent-children relation.
|
||||||
|
node* _parent;
|
||||||
|
vector<node*> _children;
|
||||||
|
|
||||||
|
//Information about about p-nodes in DFS-tree
|
||||||
|
vector<node*> _adj_list;
|
||||||
|
int _post_order_index;
|
||||||
|
int _node_id;
|
||||||
|
|
||||||
|
//List of essential nodes in c-node
|
||||||
|
vector<node*> _essential_list;
|
||||||
|
|
||||||
|
//Mark
|
||||||
|
int _mark;
|
||||||
|
static int _ref_mark;
|
||||||
|
};
|
||||||
|
|
||||||
|
class maximal_planar_subgraph_finder
|
||||||
|
{
|
||||||
|
public:
|
||||||
|
maximal_planar_subgraph_finder();
|
||||||
|
~maximal_planar_subgraph_finder();
|
||||||
|
void find_mps(ifstream* in, ofstream* out);
|
||||||
|
node* get_new_node(node_type t);
|
||||||
|
void read_from_file(ifstream* in);
|
||||||
|
void output(ofstream* out);
|
||||||
|
void output_deleted_edges(ofstream* out);
|
||||||
|
void postOrderTraversal();
|
||||||
|
void sort_adj_list();
|
||||||
|
void determine_edges();
|
||||||
|
void back_edge_traversal();
|
||||||
|
bool back_edge_traversal(node* traverse_node, int index);
|
||||||
|
void make_essential(node* p_node, node* c_node);
|
||||||
|
node* find(node* n);
|
||||||
|
void merge(pair<pair<node*, node*>, pair<node*, node*> > boundary, node* list_node);
|
||||||
|
void eliminate(node* u);
|
||||||
|
void eliminate_AE(node* u, node* v);
|
||||||
|
pair<pair<node*, node*>, pair<node*, node*> > trim(node* u);
|
||||||
|
void c_node_extension(node* c_node);
|
||||||
|
void recursively_shaving(node* u);
|
||||||
|
pair<node*, node*> shave(node* x);
|
||||||
|
pair<node*, node*> parallel_search_sentinel(node* x, node* &c);
|
||||||
|
pair<node*, node*> parallel_search_sentinel(node* n0, node* n0_prev, node* n1, node* n1_prev, node* & c);
|
||||||
|
pair<node*, node*> count_sentinel_elimination(pair<node*, node*> sentinel_1, int num_sentinel);
|
||||||
|
node* construct(node* u);
|
||||||
|
node* construct(node* c, node* p);
|
||||||
|
void parenting_labeling_shaving(node* u, node* node_i) ;
|
||||||
|
|
||||||
|
private:
|
||||||
|
vector<node*> _node_list; //List of nodes input.
|
||||||
|
vector<pair<node*, node*> > _edge_list; // Edges in DFS-tree. These edges must be contained in the maximal planar subgraph that we found.
|
||||||
|
vector<node*> _post_order_list; //The sorted version (increasing with post-order-index) of _node_list.
|
||||||
|
vector<pair<node*, node*> > _back_edge_list; // Edges other than that in DFS-tree. (The first node's index is higher than the second's.)
|
||||||
|
vector<bool> _is_back_edge_eliminate; //Record that if the back-edge has been eliminated or not.
|
||||||
|
vector<node*> _new_node_list; //Newly added nodes.
|
||||||
|
};
|
||||||
|
|
||||||
|
#endif
|
||||||
|
|
@ -0,0 +1,64 @@
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// Implementation of a MPS algorithm via PC-tree.
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
#include "mps.h"
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// Finding MPS
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
void find_mps(ifstream* in, ofstream* out) {
|
||||||
|
maximal_planar_subgraph_finder m;
|
||||||
|
m.find_mps(in, out);
|
||||||
|
}
|
||||||
|
|
||||||
|
void maximal_planar_subgraph_finder::find_mps(ifstream* in, ofstream* out) {
|
||||||
|
read_from_file(in);
|
||||||
|
postOrderTraversal();
|
||||||
|
sort_adj_list();
|
||||||
|
determine_edges();
|
||||||
|
back_edge_traversal();
|
||||||
|
output(out);
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// Imput, output
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
//First line: a single integer indicates the number of nodes.
|
||||||
|
//The rest: a pair of integers (i, j) represents an edge (i, j)
|
||||||
|
//0 <= i, j < n-1, where n is number of nodes.
|
||||||
|
void maximal_planar_subgraph_finder::read_from_file(ifstream* in) {
|
||||||
|
int node_num, n1, n2;
|
||||||
|
//Number of nodes.
|
||||||
|
(*in) >> node_num;
|
||||||
|
//initialize all the nodes.
|
||||||
|
for (int i = 0; i < node_num; ++i) {
|
||||||
|
_node_list.push_back(new node(P_NODE));
|
||||||
|
_node_list[i]->set_id(i);
|
||||||
|
}
|
||||||
|
//Set the adj-list.
|
||||||
|
while ((*in) >> n1 >> n2) {
|
||||||
|
_node_list[n1]->add_adj(_node_list[n2]);
|
||||||
|
_node_list[n2]->add_adj(_node_list[n1]);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//Output a maximal planar subgraph in the same format as input.
|
||||||
|
void maximal_planar_subgraph_finder::output(ofstream* out) {
|
||||||
|
(*out) << _node_list.size() << endl;
|
||||||
|
for (int i = 0; i < _edge_list.size(); ++i) {
|
||||||
|
(*out) << _edge_list[i].first->node_id() << " " << _edge_list[i].second->node_id() << endl;
|
||||||
|
}
|
||||||
|
for (int i = 0; i < _back_edge_list.size(); ++i) {
|
||||||
|
if (_is_back_edge_eliminate[i]) continue;
|
||||||
|
(*out) << _back_edge_list[i].first->node_id() << " " << _back_edge_list[i].second->node_id() << endl;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
void maximal_planar_subgraph_finder::output_deleted_edges(ofstream* out) {
|
||||||
|
(*out) << _node_list.size() << endl;
|
||||||
|
for (int i = 0; i < _back_edge_list.size(); ++i) {
|
||||||
|
if (!_is_back_edge_eliminate[i]) continue;
|
||||||
|
(*out) << _back_edge_list[i].first->node_id() << " " << _back_edge_list[i].second->node_id() << endl;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
@ -0,0 +1,241 @@
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// Implementation of a MPS algorithm via PC-tree.
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
#include "mps.h"
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// CONSTRUCTOR
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
node::node(node_type t) {
|
||||||
|
_type = t;
|
||||||
|
_label = pair<int, label>(INT_MAX, NOT_VISITED);
|
||||||
|
_neighbor[0] = _neighbor[1] = 0;
|
||||||
|
_AE_root[0] = _AE_root[1] = 0;
|
||||||
|
_original_node = 0;
|
||||||
|
_c_node = 0;
|
||||||
|
_parent = 0;
|
||||||
|
_post_order_index = INT_MAX;
|
||||||
|
_node_id = INT_MAX;
|
||||||
|
_mark = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// TYPE, ID, INDEX
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
node_type node::type() {return _type;}
|
||||||
|
|
||||||
|
int node::post_order_index() {return _post_order_index;}
|
||||||
|
|
||||||
|
void node::set_id(int i) {_node_id = i;}
|
||||||
|
|
||||||
|
void node::set_post_order_index(int i) {_post_order_index = i;}
|
||||||
|
|
||||||
|
//Only used when consturcting c-node
|
||||||
|
//The first node calling this function would not be labeled.
|
||||||
|
void node::recursively_labeling() {
|
||||||
|
for (int i = 0; i < _children.size(); ++i) {
|
||||||
|
_children[i]->_label.second = ARTIFICIAL_EDGE;
|
||||||
|
_children[i]->recursively_labeling();
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
int node::node_id() {return _node_id;}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// DFS-TREE
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
void node::add_adj(node* n) {_adj_list.push_back(n);}
|
||||||
|
|
||||||
|
int node::degree() {return _adj_list.size();}
|
||||||
|
|
||||||
|
node* node::adj(int i) {return _adj_list[i];}
|
||||||
|
|
||||||
|
void node::set_adj_list(vector<node*> vec) {_adj_list = vec;}
|
||||||
|
|
||||||
|
void node::DFS_visit(vector<node*> &dfsList, int &index) {
|
||||||
|
mark();
|
||||||
|
for (int i = 0; i < _adj_list.size(); ++i) {
|
||||||
|
if (!_adj_list[i]->is_marked()) {
|
||||||
|
_adj_list[i]->_parent = this;
|
||||||
|
_adj_list[i]->DFS_visit(dfsList, index);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
set_post_order_index(index);
|
||||||
|
dfsList.push_back(this);
|
||||||
|
++index;
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// PARENT-CHILDREN
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
int node::child_num() {return _children.size();}
|
||||||
|
|
||||||
|
node* node::child(int i) {return _children[i];}
|
||||||
|
|
||||||
|
node* node::parent() {return _parent;}
|
||||||
|
|
||||||
|
void node::clear_children() {
|
||||||
|
_children.clear();
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::remove_child(int i) {
|
||||||
|
_children[i] = _children[_children.size()-1];
|
||||||
|
_children.resize(_children.size()-1);
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::remove_child(node* n) {
|
||||||
|
for (int i = 0; i < _children.size(); ++i) {
|
||||||
|
if (_children[i] == n) {
|
||||||
|
_children[i] = _children[_children.size()-1];
|
||||||
|
_children.resize(_children.size()-1);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::add_child(node* n) {
|
||||||
|
_children.push_back(n);
|
||||||
|
}
|
||||||
|
|
||||||
|
vector<node*>* node::get_children_list() {
|
||||||
|
vector<node*>* ptr = new vector<node*>(_children);
|
||||||
|
return ptr;
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::set_parent(node* n) {
|
||||||
|
_parent= n;
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// BOUNDARY_PATH
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
void node::set_to_boundary_path(node* n0, node* n1) {
|
||||||
|
_parent = 0;
|
||||||
|
_children.clear();
|
||||||
|
_neighbor[0] = n0;
|
||||||
|
_neighbor[1] = n1;
|
||||||
|
set_2nd_label(BOUNDARY_PATH);
|
||||||
|
}
|
||||||
|
|
||||||
|
node* node::get_next(node* prev) {
|
||||||
|
if (_neighbor[0] != prev) return _neighbor[0];
|
||||||
|
else return _neighbor[1];
|
||||||
|
}
|
||||||
|
|
||||||
|
node* node::neighbor(int i) {return _neighbor[i];}
|
||||||
|
|
||||||
|
void node::set_neighbor(int i, node* n) {_neighbor[i] = n;}
|
||||||
|
|
||||||
|
void node::set_neighbor(node* u, node* v) {
|
||||||
|
_neighbor[0] = u;
|
||||||
|
_neighbor[1] = v;
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// ARTIFICIAL EDGE
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
node* node::AE(int i) {return _AE_root[i];}
|
||||||
|
|
||||||
|
void node::set_AE(int i, node* j) {
|
||||||
|
_AE_root[i] = j;
|
||||||
|
if (j != 0) j->set_parent(this);
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::add_AE(node* j) {
|
||||||
|
if (j == 0) return;
|
||||||
|
if (_AE_root[0] == 0) set_AE(0, j);
|
||||||
|
else if (_AE_root[1] == 0) set_AE(1, j);
|
||||||
|
}
|
||||||
|
|
||||||
|
//Inherit u's artificial edge.
|
||||||
|
void node::inherit_AE(node* u) {
|
||||||
|
if (u->_AE_root[0] != 0) add_AE(u->_AE_root[0]);
|
||||||
|
if (u->_AE_root[1] != 0) add_AE(u->_AE_root[1]);
|
||||||
|
u->_AE_root[0] = u->_AE_root[1] = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
//Set itself to be an AE-root-node in u.
|
||||||
|
//Inherite u's chilren-list.
|
||||||
|
//Do nothing if u does not have any children.
|
||||||
|
void node::init_AE(node* u) {
|
||||||
|
if (u->child_num() == 0) return;
|
||||||
|
_children = u->_children;
|
||||||
|
u->clear_children();
|
||||||
|
for (int i = 0; i < _children.size(); ++i) {
|
||||||
|
_children[i]->set_parent(this);
|
||||||
|
}
|
||||||
|
set_parent(u);
|
||||||
|
set_1st_label(_children[0]->get_1st_label());
|
||||||
|
set_2nd_label(ARTIFICIAL_EDGE);
|
||||||
|
u->add_AE(this);
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// REPLICA
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
node* node::original_node() {return _original_node;}
|
||||||
|
|
||||||
|
node* node::get_c_node() {return _c_node;}
|
||||||
|
|
||||||
|
void node::set_c_node(node* c) {_c_node = c;}
|
||||||
|
|
||||||
|
bool node::is_sentinel() {return type() == REPLICA_NODE;}
|
||||||
|
|
||||||
|
//Check if n1 and n2 correspond to the same node
|
||||||
|
bool node::is_same(node* n1, node* n2) {
|
||||||
|
node* s1 = (n1->type() == REPLICA_NODE)? n1->original_node() : n1;
|
||||||
|
node* s2 = (n2->type() == REPLICA_NODE)? n2->original_node() : n2;
|
||||||
|
return s1 == s2;
|
||||||
|
}
|
||||||
|
|
||||||
|
//Set itself to be a replica-node of u in c.
|
||||||
|
//Only inherit some basic setting, not including info about neighborhood.
|
||||||
|
void node::init_replica(node* u, node* c) {
|
||||||
|
set_post_order_index(u->post_order_index());
|
||||||
|
set_2nd_label(BOUNDARY_PATH);
|
||||||
|
_original_node = (u->type() == REPLICA_NODE)? u->original_node() : u;
|
||||||
|
_c_node = c;
|
||||||
|
}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// LABELING
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
void node::set_1st_label(int i) {_label.first = i;}
|
||||||
|
|
||||||
|
void node::set_2nd_label(label i) {_label.second = i;}
|
||||||
|
|
||||||
|
int node::get_1st_label() {return _label.first;}
|
||||||
|
|
||||||
|
label node::get_2nd_label() {return _label.second;}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// C-NODE
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
node* node::get_a_list_node() {
|
||||||
|
return _essential_list[0];
|
||||||
|
}
|
||||||
|
|
||||||
|
int node::c_node_size() {
|
||||||
|
return _essential_list.size();
|
||||||
|
}
|
||||||
|
|
||||||
|
node* node::essential(int i) {
|
||||||
|
return _essential_list[i];
|
||||||
|
}
|
||||||
|
|
||||||
|
void node::clear_essential() {_essential_list.clear();}
|
||||||
|
|
||||||
|
void node::add_essential(node* u) {_essential_list.push_back(u);}
|
||||||
|
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
// MARK
|
||||||
|
//-----------------------------------------------------------------------------------
|
||||||
|
void node::mark() {_mark = _ref_mark;}
|
||||||
|
|
||||||
|
void node::init_mark() {++_ref_mark;}
|
||||||
|
|
||||||
|
void node::un_mark() {_mark = 0;}
|
||||||
|
|
||||||
|
bool node::is_marked() {return _mark == _ref_mark;}
|
||||||
|
|
||||||
|
int node::_ref_mark = 1;
|
||||||
Loading…
Reference in New Issue