Cod sursa(job #755338)
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");
vector<int> a[111111];
bool l[111111];
int c[111111];
int n,m,i,s,x,y,st,dr,k=0,j;
void dfs(int poz)
{
int i;
for(i=0;i<a[poz].size();++i)
{
if(l[a[poz][i]]==false)
{
l[a[poz][i]]=true;
dfs(a[poz][i]);
}
}
}
int main()
{
in>>n>>m;
for(i=1;i<=m;++i)
{
in>>x>>y;
a[x].push_back(y);
a[y].push_back(x);
}
for(j=1;j<=n;++j)
{
if(l[j]==true)
{
continue;
}
++k;
dfs(j);
}
out<<k;
return 0;
}