Rave Hanker

#include <iostream>#include <map>#include <set>#include <string>using namespace std;#ifdef DBG#define PDBG(X) { cout<<X<<endl; }#else #define PDBG(X) #endiftypedef map<int, set<int> > Adj;Adj Graph;map<string, int> NodeIndex;set<int> Visited;int NodeLen,	root,	steps,	maxVal;void findMax (int parent, int child){	set<int>::iterator iter;	PDBG("Parent :"<<parent<<" child :"<<child);	if(Visited.find(child) != Visited.end() ) {		PDBG(child<<" repeats");		return;	}	if(Graph[child].find(child) != Graph[child].end())		return;	//Check if No visited,  except parent loves child	for(iter = Visited.begin(); iter != Visited.end(); iter++ ) {		if(*iter != parent && Graph[*iter].find(child)!= Graph[*iter].end()) {			PDBG("Child "<<child<<" loves "<<*iter);			return;		}	}	// check that the child does not love anybody in the Visited set 	// If it loves the root, then finish the loop    for (iter = Graph[child].begin(); iter != Graph[child].end(); iter++) {		if (*iter != root && Visited.find(*iter) != Visited.end()) {			PDBG("Child "<<child<<" loves Visited at "<<*iter<<" with root "<<root);			return;		}	}	if (Graph[child].find(root) != Graph[child].end()) {            // Only connects to root, Finalize		if (maxVal < steps+1) {			maxVal = steps+1;			PDBG("\t Value Set :"<<maxVal)		}		return;	}    	Visited.insert(child);	for (set<int>::iterator iter= Graph[child].begin(); iter!= Graph[child].end(); iter++) {		steps++;		findMax(child, *iter);		steps--;	}	Visited.erase(child);}int main(){	int n;	cin>>n;	NodeLen = 1;	for (int i=0; i<n; i++) {		string lhs, rhs;		int li, ri;		cin>>lhs>>rhs;		if ( (li = NodeIndex[lhs]) == 0)			li = (NodeIndex[lhs] = NodeLen++);		if ( (ri = NodeIndex[rhs]) == 0)			ri = (NodeIndex[rhs] = NodeLen++);		Graph[li].insert(ri);	}	maxVal = 0;	for (root = 1; root < NodeLen; root++) {		steps = 1;		if(Graph[root].find(root) != Graph[root].end())			continue;		Visited.insert (root);		PDBG("Root :"<<root);		for (set<int>::iterator iter = Graph[root].begin(); iter != Graph[root].end(); iter++)		{			findMax(root, *iter);		}		Visited.erase(root);	}	if(maxVal>2)        cout<<maxVal<<endl;	else 		cout<<0<<endl;	return 0;}