Show the number of connected components and the size of the largest one

Contractor/Contractor.h

@@ -16,7 +16,7 @@ You should have received a copy of the GNU Affero General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 or see http://www.gnu.org/licenses/agpl.txt.
-*/
+ */
 
 #ifndef CONTRACTOR_H_INCLUDED
 #define CONTRACTOR_H_INCLUDED
@@ -460,8 +460,69 @@ public:
             }
         }
     }
+
+    NodeID GetNumberOfComponents()
+    {
+        NodeID unique = 1;
+        NodeID largestRun = 0;
+        NodeID tmp = 1;
+        _components = new std::vector<NodeID>(_graph->GetNumberOfNodes(), 0);
+        for(NodeID i = 0; i < _graph->GetNumberOfNodes(); i++)
+        {
+            BFSAtNode(i);
+        }
+#ifdef _GLIBCXX_PARALLEL
+        __gnu_parallel::sort( _components->begin(), _components->end() );
+#else
+        std::sort(_components->begin(), _components->end());
+#endif
+
+        for(NodeID i = 0; i < _graph->GetNumberOfNodes()-1; i++)
+        {
+            if( _components->at(i) != _components->at(i+1)){
+                if(tmp > largestRun)
+                {
+                    largestRun = tmp;
+                } else {
+                    cout << tmp << " " << flush;
+                }
+                tmp = 1;
+                unique++;
+            }
+            else
+                tmp++;
+        }
+        if(tmp > largestRun)
+            largestRun = tmp;
+        _components->clear();
+        cout << "Largest component has size: " << largestRun << endl;
+        return unique;
+    }
+
 private:
 
+    void BFSAtNode(const NodeID n){
+        std::stack<NodeID> * bfsStack = new std::stack<NodeID>();
+        if(_components->at(n) != 0)
+            return;
+        _components->at(n) = n+1;
+        bfsStack->push(n);
+        while(!bfsStack->empty())
+        {
+            NodeID node = bfsStack->top();
+            bfsStack->pop();
+            for(_DynamicGraph::EdgeIterator e = _graph->BeginEdges(node); e < _graph->EndEdges(node); e++)
+            {
+                if(_components->at(_graph->GetTarget(e))!=0)
+                    continue;
+                _components->at(_graph->GetTarget(e)) = n+1;
+                bfsStack->push(_graph->GetTarget(e));
+            }
+        }
+        delete bfsStack;
+    }
+
+
     double _Timestamp() {
         return time(NULL);
     }
@@ -721,6 +782,8 @@ private:
     }
 
     _DynamicGraph* _graph;
+    std::vector<NodeID> * _components;
+
 };
 
 #endif // CONTRACTOR_H_INCLUDED

createHierarchy.cpp

@@ -85,6 +85,9 @@ int main (int argc, char *argv[])
     int2ExtNodeMap->clear();
 
     Contractor* contractor = new Contractor( n, edgeList );
+
+    cout << "Number of connected components: " << contractor->GetNumberOfComponents() << endl;
+
     contractor->Run();
 
     contractor->checkForAllOrigEdges(edgeList);