Number of Hamiltonion Paths

Hamiltion_paths

#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;
struct city{
int l;
int r;
int len;
}C[55];
class HamiltonPath {
public:
	int countPaths(vector <string>);
};

int HamiltonPath::countPaths(vector <string> roads) {
	vector <string>::iterator it;
	string s;
	long long i,j,k=0,ans=0,chains=0,maap[100]={0};
	for(i=0;i<55;i++)
	{C[i].l=-1;C[i].r=-1;C[i].len=1;}
	for(it=roads.begin();it!=roads.end();++it,k++)
	{
		s=*it;
		for(j=0;j<s.length();j++)
		{
			if(s[j]=='N')
				continue;
			
			if(C[j].l==k || C[j].r==k )
				continue;
			int x= j;
			if( C[x].l==-1 && C[x].r==-1 && C[k].l==-1 && C[k].r==-1 )
				chains++;
			
			cout<<chains<<"* ";
			if(C[k].l!=-1 && C[k].r!=-1)
				return 0;
			cout<<"!";
			if(C[k].l== -1)
				{
				   	if(C[j].l==-1)
				   		C[j].l=k;
				   	else if(C[j].r==-1)
				   		C[j].r=k;
				   	else 
				   		return 0;
					C[k].l=j;
					
					C[k].len++;
					C[j].len++;
				}
			else if(C[k].r== -1)
				{
					if(C[j].l==-1)
				   		C[j].l=k;
				   	else if(C[j].r==-1)
				   		C[j].r=k;
				   	else 
				   		return 0;
					C[k].r=j;
					
					C[k].len++;
					C[j].len++;
				}
			else
				return 0;
				
			if(C[k].len >= roads.size() || C[j].len >= roads.size() )
				return 0;
			cout<<"#"<<C[k].len<<"#"<<C[j].len<<"---";
			maap[x]=1;
			maap[k]=1;
		}
	}
	ans=1;
	cout<<"!";
	long long N=0;
	for(i=0;i<roads.size();i++)
		if(maap[i]==0)
			N++;
		
	for(i=1;i<=(N+chains);i++)
		ans = (ans*i) % 1000000007;
	ans = ans* ( (long long)pow(2,chains) % 1000000007 ) % 1000000007;
	
	 return ans; 
}

<%:testing-code%>
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