void loopdetect(GenericTree& twd){
vector<bool> visited(twd.num_nodes(), false);
for(int i=0; i<twd.num_nodes(); i++){
if(visited[i]==true)
continue;
visited[i]=true;
queue<pair<int, int> > q;
q.push(pair<int, int>(-1,i));//first is father, second is current_node
while(q.size()>0){
pair<int, int> father_current=q.front();
q.pop();
for(TreeEdgeList::iterator it=twd.get_neighbors(father_current.second).begin(); it!=twd.get_neighbors(father_current.second).end(); it++){
if(it->nodeID==father_current.first)
continue;
if(visited[it->nodeID]==true){
cout<<"Loop Detected at: "<<it->nodeID<<endl;
exit(-1);
}
visited[it->nodeID]=true;
q.push(pair<int, int>(father_current.second, it->nodeID));
}
}
}
}
void buildBalancedTreeDecomposition(GenericTree& twd, GenericTree& btd, const vector<set<int> >& nodedirectory){
for(int i=0; i<twd.num_nodes(); i++){
if(twd[i].visited==true)
continue;
//calculate the number of vertices in the connected component (BFS)
twd[i].visited=true;
int CC_size=1;
queue<int> q;
q.push(i);
while(q.size()>0){
int j=q.front();
q.pop();
for(TreeEdgeList::iterator tit=twd.get_neighbors(j).begin(); tit!=twd.get_neighbors(j).end(); tit++){
if(twd[tit->nodeID].visited==true)
continue;
twd[tit->nodeID].visited=true;
CC_size++;
q.push(tit->nodeID);
}
}
//calculate the number of vertices in the connected component done
//Fill in the neighbor size info and locate the centroid
int from_vertex=-1;
int centroid=-1;
int centroid_weight=MAX_VAL;
SubtreeMeasure(twd, centroid, centroid_weight, i, from_vertex, CC_size, nodedirectory);
//Fill in the neighbor size info and locate the centroid done
//Iteratively build balanced decomposition tree
BalancedTreeConstr(twd, btd, centroid, 0, nodedirectory);
SubtreeMeasure(btd, centroid, centroid_weight, i, from_vertex, CC_size, nodedirectory);
//Iteratively build balanced decomposition tree done
}
}
int main(int argc, char* argv[]) {
if (argc == 1) {
usage();
return 1;
}
string query_filename, input_filename;
int input_para_counter=1;
// int source_vertex=-1;
// int destination_vertex=-1;
int rw_queryfile=-1;
construction_type graph_input_format=ADJ_GRAPH;
graph_type direct_info=UNDIRECT;
int query_num=100000;
int verify_enable=1;
while (input_para_counter < argc) {
if (strcmp("-h", argv[input_para_counter]) == 0) {
usage();
return 1;
}
if (strcmp("-g", argv[input_para_counter]) == 0) {
input_para_counter++;
graph_input_format=static_cast<construction_type>(atoi(argv[input_para_counter++]));
}else if (strcmp("-d", argv[input_para_counter]) == 0) {
input_para_counter++;
direct_info=static_cast<graph_type>(atoi(argv[input_para_counter++]));
}else if (strcmp("-l", argv[input_para_counter]) == 0){
input_para_counter++;
rw_queryfile= atoi(argv[input_para_counter++]);
}else if (strcmp("-q", argv[input_para_counter]) == 0){
input_para_counter++;
query_filename= argv[input_para_counter++];
}else if (strcmp("-n", argv[input_para_counter]) == 0){
input_para_counter++;
query_num= atoi(argv[input_para_counter++]);
}else if (strcmp("-v", argv[input_para_counter]) == 0){
input_para_counter++;
verify_enable= atoi(argv[input_para_counter++]);
}else{
input_filename = argv[input_para_counter++];
// source_vertex = atoi(argv[input_para_counter++]);
// destination_vertex = atoi(argv[input_para_counter++]);
}
}
ifstream infile(input_filename.c_str());
if (!infile) {
cout << "Error: Cannot open " << input_filename << endl;
return -1;
}
vector<int> src;
vector<int> trg;
Graph g(infile, graph_input_format, direct_info);
if(direct_info==UNDIRECT)
cout << "#vertex size:" << g.num_vertices() << "\t#edge size:" << g.num_edges() << endl;
else
cout << "#vertex size:" << g.num_vertices() << "\t#undirect edge size:" << g.num_edges() << "\t#direct edge size:"<< g.num_directed_edges() << endl;
//Symmetric test is enforced right now. In the future, we can allowed directed graphs
//Note the program requires that a vertex itself does not appear in its adjacent list and the adjacent list is in ascending order.
if(!g.isSymmetric()){
cout<<"Internal Error: Intend to treat a directed graph as undirected."<<endl;
exit(-1);
}
if(rw_queryfile==1){
GraphUtil::generate_queryfile(src, trg, g.num_vertices(), query_filename.c_str(), query_num);
}else if(rw_queryfile==0){
GraphUtil::load_queryfile(src, trg, query_filename.c_str());
}else{//generate query without loading from or saving into files.
GraphUtil::generate_query(src, trg, g.num_vertices(), query_num);
}
//Start index construction
struct timeval after_index_const_time, before_index_const_time;
gettimeofday(&before_index_const_time, NULL);
GenericTree twd;
vector<set<int> > nodedirectory; //middle result.
Graph g1=g;
int max_bag_size=buildTreeWidthDecomposition(g1, twd, nodedirectory);
cout<<"max_bag_size of this decomposition: "<<max_bag_size<<endl;
vector<vector<int> > node_mapping_directory(nodedirectory.size(), vector<int>());
//twd.printTree();
cout<<"Tree Width Decomposition successful. "<<endl;
cout<<"twd.num_nodes(): "<<twd.num_nodes()<<endl;
GenericTree btd(twd.num_nodes());
buildBalancedTreeDecomposition(twd, btd, nodedirectory);
cout<<"Balanced Tree decomposition successful. "<<endl;
cout<<"btd.num_nodes(): "<<btd.num_nodes()<<endl;
//btd.printTree();
BinaryTree btree(btd.num_nodes());
vector<int> virtualnode_to_realnode;//The virtual node to real node mapping table. //middle result.
buildBinaryTree(btd, btree, virtualnode_to_realnode);
cout<<"Binary Tree construction successful. "<<endl;
cout<<"btree.num_nodes(): "<<btree.num_nodes()<<endl;
cout<<"btree.access_height(): "<<btree.access_height()<<endl;
//btree.printTree();
if(btree.access_height()>63){
cout<<"The current program maximally supports a balanced binary tree with height no more than 63, i.e., about 2^61 vertices in the original graph."<<endl;
cout<<"This number shall satisfy almost all current applications. Please verify you really need to run such a giant graph. If yes, a simple update on the Machine_WORD data structure will make it work."<<endl;
cout<<"Program exit."<<endl;
exit(0);
}
vector<MACHINE_WORD> TreeNodeBitLabel(btree.num_nodes(), 0);//middle result
BitOperators::set_one(TreeNodeBitLabel[btree.access_root()], btree.access_height());
cout<<"Start building Tree Node Bit label"<<endl;
BuildTreeNodeBitlabel(btree, btree.access_root(), TreeNodeBitLabel);
cout<<"End building Tree Node Bit label"<<endl;
//hashmap implementation
hash_map<int, int> BitLabelTreeNode;//Map bit label to real tree node. Part of final label.
for (int i=0; i<int(TreeNodeBitLabel.size()); i++){
if (i>=btd.num_nodes()){
BitLabelTreeNode[TreeNodeBitLabel[i]]=virtualnode_to_realnode[i-btd.num_nodes()];//virtualnode_to_realnode gets -1 if no real node can be mapped.
}
else
BitLabelTreeNode[TreeNodeBitLabel[i]]=i;
}
vector<vector<VertexDistancePair> > LabelGT(g.num_vertices());//The first is vertex ID, and the second is distance. //middle result
vector<vector<VertexDistancePair> > LabelGT_From(g.num_vertices());//middle result
vector<vector<VertexDistancePair> > LabelGT_To(g.num_vertices());//middle result
vector<vertex_mapping_info> vertex_mapping_table(g.num_vertices());//The table recording the mapping between vertex, and btree level and label offset. //Part of final label.
vector<int> vertex_to_nodeID(g.num_vertices());//middle result
cout<<"Start building LabelGT"<<endl;
if(direct_info==DIRECT)
BuildLabelGTDirect(g, btree, nodedirectory, node_mapping_directory, LabelGT_From, LabelGT_To, vertex_mapping_table, vertex_to_nodeID);
else
BuildLabelGT(g, btree, nodedirectory, node_mapping_directory, LabelGT, vertex_mapping_table, vertex_to_nodeID);
cout<<"End building LabelGT"<<endl;
for(size_t i=0; i<vertex_mapping_table.size(); i++){
vertex_mapping_table[i].NodeBitLabel=TreeNodeBitLabel[vertex_to_nodeID[i]];
}
//sort and printout LabelGT or LabelGT_From, LabelGT_To
if(direct_info==DIRECT){
for(size_t i=0; i<LabelGT_From.size(); i++){
sort(LabelGT_From[i].begin(), LabelGT_From[i].end(), VertexDistanceCompare);
}
for(size_t i=0; i<LabelGT_To.size(); i++){
sort(LabelGT_To[i].begin(), LabelGT_To[i].end(), VertexDistanceCompare);
}
}else{
for(size_t i=0; i<LabelGT.size(); i++){
sort(LabelGT[i].begin(), LabelGT[i].end(), VertexDistanceCompare);
}
}
//printout LabelGT done
//release memory first time
g1.clear();
TreeNodeBitLabel.clear();
virtualnode_to_realnode.clear();
btd.clear();
twd.clear();
cout<<"Start prequery"<<endl;
vector<vector<vector<int> > > LabelGTUpdate(g.num_vertices());//It is a partial update in this version
vector<vector<vector<int> > > LabelGT_From_Update(g.num_vertices());
vector<vector<FlatVector> > LabelGT_From_Mask(g.num_vertices());
vector<vector<vector<int> > > LabelGT_To_Update(g.num_vertices());
vector<vector<FlatVector> > LabelGT_To_Mask(g.num_vertices());
for (int v=0; v<g.num_vertices(); v++){
if(v%1000==0)
cout<<"prequery on "<<v<<endl;
if(direct_info==DIRECT){
LabelGT_From_Update[v].resize(vertex_mapping_table[v].level+1);
LabelGT_From_Mask[v].resize(vertex_mapping_table[v].level+1);
LabelGT_To_Update[v].resize(vertex_mapping_table[v].level+1);
LabelGT_To_Mask[v].resize(vertex_mapping_table[v].level+1);
}else
LabelGTUpdate[v].resize(vertex_mapping_table[v].level+1);
int current_node=int(vertex_to_nodeID[v]);
while(current_node!=-1){
if(current_node<int(nodedirectory.size())){
if(direct_info==DIRECT){
set<int>::iterator sit=nodedirectory[current_node].begin();
vector<int>::iterator vit=node_mapping_directory[current_node].begin();
int nodedirectory_offset=0;
while(sit!=nodedirectory[current_node].end()){
int To_distance=prequeryDirect(LabelGT_From, LabelGT_To, v, *sit);
int From_distance=prequeryDirect(LabelGT_From, LabelGT_To, *sit, v);
if(vit!=node_mapping_directory[current_node].end()){
if(*sit==*vit){
LabelGT_To_Update[v][btree[current_node].level].push_back(To_distance);
if (To_distance<MAX_VAL)
LabelGT_To_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
LabelGT_From_Update[v][btree[current_node].level].push_back(From_distance);
if (From_distance<MAX_VAL)
LabelGT_From_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
sit++;
vit++;
}else if (*sit<*vit){
if (To_distance<MAX_VAL)
LabelGT_To_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
if (From_distance<MAX_VAL)
LabelGT_From_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
sit++;
}else{
cout<<"This should not happen because one is the subset of the other."<<endl;
exit(-1);
}
}else{
if (To_distance<MAX_VAL)
LabelGT_To_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
if (From_distance<MAX_VAL)
LabelGT_From_Mask[v][btree[current_node].level].insert(nodedirectory_offset);
sit++;
}
nodedirectory_offset++;
}
}else{
for(vector<int>::iterator vit=node_mapping_directory[current_node].begin(); vit!=node_mapping_directory[current_node].end(); vit++){
LabelGTUpdate[v][btree[current_node].level].push_back(prequery(LabelGT, v, *vit));
}
}
}
current_node=btree[current_node].parent;
}
}
cout<<"End prequery"<<endl;
//release memory second time
LabelGT.clear();
LabelGT_From.clear();
LabelGT_To.clear();
vertex_to_nodeID.clear();
node_mapping_directory.clear();
int tree_height=btree.access_height();
if(int(BitLabelTreeNode.size())<btree.num_nodes())
cout<<"HashMap has compressed the index size"<<endl;
else if (int(BitLabelTreeNode.size())>btree.num_nodes())
cout<<"HashMap has introduced more index size than the tree node number."<<endl;
btree.clear();
vector<vector<int> > node_directory(nodedirectory.size());
vector<int> TreeNodeLevel(nodedirectory.size());//Only real node levels are necessary.
int node_directory_size=0;
for(size_t i=0; i<nodedirectory.size(); i++){
TreeNodeLevel[i]=btree[i].level;
for(set<int>::iterator sit=nodedirectory[i].begin(); sit!=nodedirectory[i].end(); sit++){
node_directory[i].push_back(*sit);
node_directory_size++;
}
}
nodedirectory.clear();
//release memory done
//End index construction
gettimeofday(&after_index_const_time, NULL);
double index_construct_time=(after_index_const_time.tv_sec - before_index_const_time.tv_sec)*1000.0 + (after_index_const_time.tv_usec - before_index_const_time.tv_usec)*1.0/1000.0;
cout<<"Index construction completed in : "<<index_construct_time<<" (ms). This time includes outputting the running information."<<endl;
//Data structure must be used for ALL query: vertex_mapping_table, BitLabelTreeNode, tree_height;
//Data structure must be used for distance query on undirected graphs: LabelGTUpdate, node_directory;
//Data structure must be used for distance query on directed graphs: LabelGT_From_Update, LabelGT_To_Update, node_directory;
//Optional Data structure for distance query on directed graphs: LabelGT_From_Mask, LabelGT_To_Mask, TreeNodeLevel;
//Calculate TC size:
long int TC_size=0;
if(direct_info==DIRECT){
int From_size_1=0;
int From_size_2=0;
for (size_t i=0; i<LabelGT_From_Update.size(); i++){
for(size_t j=0; j<LabelGT_From_Update[i].size(); j++){
From_size_1+=LabelGT_From_Update[i][j].size();
From_size_2+=LabelGT_From_Mask[i][j].size();
}
}
int To_size_1=0;
int To_size_2=0;
for (size_t i=0; i<LabelGT_To_Update.size(); i++){
for(size_t j=0; j<LabelGT_To_Update[i].size(); j++){
To_size_1+=LabelGT_To_Update[i][j].size();
To_size_2+=LabelGT_To_Mask[i][j].size();
}
}
if(From_size_1!=To_size_1){
cout<<"From size and To size do not match. Error in direct labeling."<<endl;
exit(-1);
}else{
TC_size=From_size_1+To_size_1+From_size_2+To_size_2;
}
}else{
for (size_t i=0; i<LabelGTUpdate.size(); i++){
for(size_t j=0; j<LabelGTUpdate[i].size(); j++){
TC_size+=LabelGTUpdate[i][j].size();
}
}
}
if(direct_info==DIRECT)
cout<<"Total indexing size: "<<TC_size+vertex_mapping_table.size()*3+BitLabelTreeNode.size()+TreeNodeLevel.size()+node_directory_size+1<<endl;
else
cout<<"Total indexing size: "<<TC_size+vertex_mapping_table.size()*3+BitLabelTreeNode.size()+node_directory_size+1<<endl;
cout<<"Start query..."<<endl;
struct timeval after_time, before_time;
int twd_distance, bfs_distance;
vector<int>::iterator sit, tit;
if(direct_info==DIRECT){
gettimeofday(&before_time,NULL);
for(sit = src.begin(), tit = trg.begin(); sit != src.end(); ++sit, ++tit)
twd_distance=queryDirectMask(vertex_mapping_table, BitLabelTreeNode, TreeNodeLevel, node_directory, LabelGT_From_Update, LabelGT_To_Update, LabelGT_From_Mask, LabelGT_To_Mask, tree_height, *sit, *tit);
gettimeofday(&after_time,NULL);
float query_time=(after_time.tv_sec - before_time.tv_sec)*1000.0 + (after_time.tv_usec - before_time.tv_usec)*1.0/1000.0;
cout<<"twd distance query time: "<<query_time<<endl;
}else{
gettimeofday(&before_time,NULL);
for(sit = src.begin(), tit = trg.begin(); sit != src.end(); ++sit, ++tit)
twd_distance=query(vertex_mapping_table, BitLabelTreeNode, node_directory, LabelGTUpdate, tree_height, *sit, *tit);
gettimeofday(&after_time,NULL);
float query_time=(after_time.tv_sec - before_time.tv_sec)*1000.0 + (after_time.tv_usec - before_time.tv_usec)*1.0/1000.0;
cout<<"twd distance query time: "<<query_time<<endl;
}
cout<<"End Query..."<<endl;
if(verify_enable==1){
cout<<"Start query verification."<<endl;
if(direct_info==DIRECT){
for(sit = src.begin(), tit = trg.begin(); sit != src.end(); ++sit, ++tit){
twd_distance=queryDirectMask(vertex_mapping_table, BitLabelTreeNode, TreeNodeLevel, node_directory, LabelGT_From_Update, LabelGT_To_Update, LabelGT_From_Mask, LabelGT_To_Mask, tree_height, *sit, *tit);
bfs_distance=GraphUtil::BFSDistanceDirect(g, *sit, *tit);
if(twd_distance!=bfs_distance){
cout<<"twd_distance direct: "<<twd_distance<<endl;
cout<<"bfs_distance direct: "<<bfs_distance<<endl;
}
}
}else{
for(sit = src.begin(), tit = trg.begin(); sit != src.end(); ++sit, ++tit){
twd_distance=query(vertex_mapping_table, BitLabelTreeNode, node_directory, LabelGTUpdate, tree_height, *sit, *tit);
bfs_distance=GraphUtil::BFSDistance(g, *sit, *tit);
if(twd_distance!=bfs_distance){
cout<<"twd_distance: "<<twd_distance<<endl;
cout<<"bfs_distance: "<<bfs_distance<<endl;
}
}
}
cout<<"end query verification."<<endl;
}
else{
cout<<"verification option waived."<<endl;
}
//find the minimum distance
cout<<"end of the program"<<endl;
}
int buildTreeWidthDecomposition(Graph& g, GenericTree& twd, vector<set<int> >& nodedirectory){//return the max_bag_size of this decomposition
set<VertexDegreePair,VertexDegreePairComp> DegreeRank;//first is degree; second is vertex id;
vector<int> DegreeList(g.num_vertices(),0);
int max_bag_size=-1;
for(int i=0; i<g.num_vertices(); i++){
int current_degree=g.get_degree(i);
DegreeRank.insert(VertexDegreePair(i, current_degree));
DegreeList[i]=current_degree;
}
while(DegreeRank.size()>0){
set<VertexDegreePair,VertexDegreePairComp>::iterator minDegreeVertex=DegreeRank.begin();
DegreeRank.erase(DegreeRank.begin());
int current_vertexID=minDegreeVertex->first;
//build treenode
nodedirectory.push_back(set<int>());
int current_nodeID=nodedirectory.size()-1;
nodedirectory.back().insert(current_vertexID);
for(EdgeList::iterator vit=g.get_neighbors(current_vertexID).begin(); vit<g.get_neighbors(current_vertexID).end(); vit++){
nodedirectory.back().insert(*vit);
g[*vit].nodes.push_back(current_nodeID);
//update on graph
EdgeList::iterator iit=g.get_neighbors(current_vertexID).begin();
EdgeList::iterator jit=g.get_neighbors(*vit).begin();
EdgeList combined;
while(iit<g.get_neighbors(current_vertexID).end() && jit<g.get_neighbors(*vit).end()){
//It is assumed that a vertex itself does not appear in its adjacent list and the adjacent list is in ascending order.
if(*iit==*vit){
iit++;
continue;
}else if (*jit==current_vertexID){
jit++;
continue;
}
if(*iit<*jit){
combined.push_back(*iit);
iit++;
}else if(*iit>*jit){
combined.push_back(*jit);
jit++;
}else{//implies *iit==*jit
combined.push_back(*iit);
iit++;
jit++;
}
}
if(iit<g.get_neighbors(current_vertexID).end() && jit<g.get_neighbors(*vit).end()){
cout<<"Internal Logic Error. Exit."<<endl;
exit(-1);
}
for(; iit<g.get_neighbors(current_vertexID).end(); iit++){
if(*iit!=*vit)
combined.push_back(*iit);
}
for(; jit<g.get_neighbors(*vit).end(); jit++){
if(*jit!=current_vertexID)
combined.push_back(*jit);
}
g.get_neighbors(*vit)=combined;
//update on graph done
//update on nodes
vector<int> reduced;
vector<int>::iterator itern=g[*vit].nodes.begin();
vector<int>::iterator jtern=g[current_vertexID].nodes.begin();
while(itern<g[*vit].nodes.end() && jtern<g[current_vertexID].nodes.end()){
if(*itern<*jtern){
reduced.push_back(*itern);
itern++;
}
else if (*itern>*jtern){
jtern++;
}
else{//implies *itern==*jtern
itern++;
jtern++;
}
}
for(; itern<g[*vit].nodes.end(); itern++)
reduced.push_back(*itern);
g[*vit].nodes=reduced;
//update on nodes done
//other update
set<VertexDegreePair,VertexDegreePairComp>::iterator fit=DegreeRank.find(VertexDegreePair(*vit, DegreeList[*vit]));
DegreeRank.erase(fit);
DegreeRank.insert(VertexDegreePair(*vit, g.get_degree(*vit)));
DegreeList[*vit]=g.get_degree(*vit);
//other update done
}
max_bag_size=int(nodedirectory.back().size())>max_bag_size? int(nodedirectory.back().size()) : max_bag_size;
//build treenode done
//build decomposition tree
twd.addNode(twd.num_nodes());
for(vector<int>::iterator nit=g[current_vertexID].nodes.begin(); nit<g[current_vertexID].nodes.end(); nit++){
twd.addEdge(current_nodeID, *nit);//current_nodeID shall always be larger than *nit;
twd.addEdge(*nit, current_nodeID);
}
//build decomposition tree done
//clear deleted vertex
g[current_vertexID].nodes.clear();
g.get_neighbors(current_vertexID).clear();
//clear deleted vertex
}
return max_bag_size;
}
void buildBinaryTree(GenericTree& btd, BinaryTree& btree, vector<int>& virtualnode_to_realnode){
multimap<int, int> subsize_root;////The first int is subtree size, and the second is node ID.
for(int current_node=0; current_node<btd.num_nodes(); current_node++){
int current_node_level=btd[current_node].nodelevel;
multimap<int, int> subsize_node;//The first int is subtree size, and the second is node ID.
int parent=-1;
int total_size=0;
for(TreeEdgeList::iterator tit=btd.get_neighbors(current_node).begin(); tit!=btd.get_neighbors(current_node).end(); tit++){
if(btd[tit->nodeID].nodelevel>current_node_level){
subsize_node.insert(pair<int, int>(tit->subtree_size, tit->nodeID));
total_size+=tit->subtree_size;
}else if (btd[tit->nodeID].nodelevel==current_node_level){
cout<<"Internal logic error 1 ocurrs on binary tree construction."<<endl;
}else{//implies btd[tit->nodeID].nodelevel<current_node_level
if (parent==-1){
parent=tit->nodeID;
}else{
cout<<"Internal logic error 2 (multiple parents) ocurrs on binary tree construction."<<endl;
}
}
}
if (parent==-1){//implies root node
subsize_root.insert(pair<int, int>(total_size+1, current_node));
}
btree[current_node].parent=parent;
if(subsize_node.size()==1){
btree[current_node].left_child=(subsize_node.begin())->second;
}else if (subsize_node.size()==2){
multimap<int, int>::iterator mit=subsize_node.begin();
btree[current_node].left_child=mit->second;
mit++;
btree[current_node].right_child=mit->second;
}else if (subsize_node.size()>2){
while(subsize_node.size()>2){
int first_size=(subsize_node.begin())->first;
int first_node=(subsize_node.begin())->second;
subsize_node.erase(subsize_node.begin());
int second_size=(subsize_node.begin())->first;
int second_node=(subsize_node.begin())->second;
subsize_node.erase(subsize_node.begin());
int new_node_id=btree.num_nodes();
//add a virtual node
btree.addNode(new_node_id);
virtualnode_to_realnode.push_back(current_node);
//add a virtual node done
btree[new_node_id].left_child=first_node;
btree[new_node_id].right_child=second_node;
btree[first_node].parent=new_node_id;
btree[second_node].parent=new_node_id;
subsize_node.insert(pair<int, int>(first_size+second_size, new_node_id));
}
multimap<int, int>::iterator mit=subsize_node.begin();
btree[current_node].left_child=mit->second;
btree[mit->second].parent=current_node;
mit++;
btree[current_node].right_child=mit->second;
btree[mit->second].parent=current_node;
}
}
int root=-1;
if(subsize_root.size()==1){
root=(subsize_root.begin())->second;
}else if (subsize_root.size()>1){
while(subsize_root.size()>1){
int first_size=(subsize_root.begin())->first;
int first_node=(subsize_root.begin())->second;
subsize_root.erase(subsize_root.begin());
int second_size=(subsize_root.begin())->first;
int second_node=(subsize_root.begin())->second;
subsize_root.erase(subsize_root.begin());
int new_node_id=btree.num_nodes();
//add a virtual node
btree.addNode(new_node_id);
virtualnode_to_realnode.push_back(-1);//If the root node is a virtual node, there is no real node can be associated with it.
//add a virtual node done
btree[new_node_id].left_child=first_node;
btree[new_node_id].right_child=second_node;
btree[first_node].parent=new_node_id;
btree[second_node].parent=new_node_id;
subsize_root.insert(pair<int, int>(first_size+second_size, new_node_id));
root=new_node_id;
}
}
if(root<0){
cout<<"The btree is empty. Please check input."<<endl;
return;
}else{
btree.access_root()=root;
btree[root].level=0;
int maximum_level=0;
queue<int> q;
q.push(root);
while(q.size()>0){
int j=q.front();
q.pop();
maximum_level=maximum_level>btree[j].level?maximum_level:btree[j].level;
if (btree[j].left_child>=0){
btree[btree[j].left_child].level=btree[j].level+1;
q.push(btree[j].left_child);
}
if (btree[j].right_child>=0){
btree[btree[j].right_child].level=btree[j].level+1;
q.push(btree[j].right_child);
}
}
btree.access_height()=maximum_level;
}
}