ComponenteConexe2

#include <fstream>
#define Nmax 101
using namespace std;
int n,A[Nmax][Nmax],x[Nmax],v[Nmax],nr_varfuri[Nmax],nr_muchii[Nmax];

void BF(int varf,int nrc) /// Parcurgem in latime
{
	int st=1,dr=1;
	v[varf]=nrc;
	x[1]=varf;
	while(st<=dr)
	{
		int k=x[st];
		for(int i=1;i<=n;++i)
			if(v[i]==0&&A[k][i]==1)
				++dr,v[i]=nrc,x[dr]=i;
		++st;
	}
}

int main()
{
    int x,y;
    ifstream f("componenteconexe2.in");
    f>>n;
    while(f>>x>>y)
    	A[x][y]=A[y][x]=1;
    f.close();
    int nrc=0;
    for(int i=1;i<=n;++i) /// Aflam componentele conexe
		if(v[i]==0)
			++nrc,BF(i,nrc);
	for(int i=1;i<=n;++i) /// Aflam cate varfuri are fiecare componenta conexa
		++nr_varfuri[v[i]];
	for(int i=1;i<n;++i) /// Aflam cate muchii are fiecare componenta conexa
		for(int j=i+1;j<=n;++j)
			if(A[i][j]==1)
				++nr_muchii[v[i]];
	int NR=0;
	for(int i=1;i<=nrc;++i) /// Din fiecare componenta eliminam atatea muchii astfel incat sa ramana arbore
		NR+=nr_muchii[i]-nr_varfuri[i]+1;
    ofstream g("componenteconexe2.out");
	g<<NR;
	g.close();
	return 0;
}