void SubtreeUpdateMeasure(GenericTree& twd, int& centroid, int& centroid_weight, const int& current_vertex, const int& from_vertex, const int& total_size, int level, const vector<set<int> >& nodedirectory){
TreeEdgeList::iterator iter_from;
int branch_total_size_other_than_from=0;
int max_branch=0;
for(TreeEdgeList::iterator tit=twd.get_neighbors(current_vertex).begin(); tit!=twd.get_neighbors(current_vertex).end(); tit++){
if(tit->nodeID!=from_vertex && twd[tit->nodeID].active==true){
SubtreeUpdateMeasure(twd, centroid, centroid_weight, tit->nodeID, current_vertex, total_size, level, nodedirectory);
max_branch=(max_branch>tit->subtree_size)? max_branch:tit->subtree_size;
branch_total_size_other_than_from+=tit->subtree_size;
}
else if (tit->nodeID==from_vertex)//This condition test cannot be missed, otherwise results in an logic error.
iter_from=tit;
}
if (from_vertex>=0){
iter_from->subtree_size=total_size-branch_total_size_other_than_from-1;
max_branch=(max_branch>iter_from->subtree_size)? max_branch:iter_from->subtree_size;
}
if(max_branch<=total_size/2){//use the centroid with smallest bag for tie break;
if(int(nodedirectory[current_vertex].size())<centroid_weight){
centroid=current_vertex;
centroid_weight=nodedirectory[current_vertex].size();
}
}
}
int SubtreeMeasure(GenericTree& gt, int& centroid, int& centroid_weight, const int& current_vertex, const int& from_vertex, const int& total_size, const vector<set<int> >& nodedirectory){
TreeEdgeList::iterator iter_from;
int branch_total_size_other_than_from=0;
int max_branch=0;
for(TreeEdgeList::iterator tit=gt.get_neighbors(current_vertex).begin(); tit!=gt.get_neighbors(current_vertex).end(); tit++){
if(tit->nodeID!=from_vertex){
tit->subtree_size=SubtreeMeasure(gt, centroid, centroid_weight, tit->nodeID, current_vertex, total_size, nodedirectory);
max_branch=(max_branch>tit->subtree_size)? max_branch:tit->subtree_size;
branch_total_size_other_than_from+=tit->subtree_size;
}
else
iter_from=tit;
}
if (from_vertex>=0){
iter_from->subtree_size=total_size-branch_total_size_other_than_from-1;
max_branch=(max_branch>iter_from->subtree_size)? max_branch:iter_from->subtree_size;
}
if(max_branch<=total_size/2){//use the centroid with smallest bag for tie break;
if(int(nodedirectory[current_vertex].size())<centroid_weight){
centroid=current_vertex;
centroid_weight=nodedirectory[current_vertex].size();
}
}
return branch_total_size_other_than_from+1;
}
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 BalancedTreeConstr(GenericTree& twd, GenericTree& btd, const int& centroid, int level, const vector<set<int> >& nodedirectory){
twd[centroid].active=false;
for(TreeEdgeList::iterator tit=twd.get_neighbors(centroid).begin(); tit!=twd.get_neighbors(centroid).end(); tit++){
if(twd[tit->nodeID].active==true){
int subcentroid=-1;
int subcentroid_weight=MAX_VAL;
SubtreeUpdateMeasure(twd, subcentroid, subcentroid_weight, tit->nodeID, centroid, tit->subtree_size, level, nodedirectory);
neighbor btd_adj_node;
neighbor btd_parent;
btd_adj_node.nodeID=subcentroid;
btd_parent.nodeID=centroid;
btd.get_neighbors(centroid).push_back(btd_adj_node);
btd.get_neighbors(btd_adj_node.nodeID).push_back(btd_parent);
btd[centroid].nodelevel=level;
btd[subcentroid].nodelevel=level+1;
BalancedTreeConstr(twd, btd, subcentroid, level+1, nodedirectory);
}
}
}
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
}
}
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;
}
}