Cod sursa(job #787539)
#include <fstream>
#include <vector>
#include <stack>
#include <list>
using namespace std;
vector< list<unsigned int> > Graph;
vector<bool> Visited;
int n, m, comp;
void Read(){
ifstream f ("dfs.in");
int x, y;
f >> n >> m;
Graph.resize(n+1);
for(int i = 1; i <= m; ++i){
f >> x >> y;
Graph[x].push_back(y);
Graph[y].push_back(x);
}
f.close();
}
void Dfs(){
stack<unsigned int> St;
Visited.resize(n+1, false);
list<unsigned int>::iterator it;
for(int i = 1; i <= n; ++i){
if(!Visited[i]){
St.push(i);
comp++;
Visited[i] = true;
do{
int x = St.top();
St.pop();
for(it = Graph[x].begin(); it != Graph[x].end(); ++it){
if(!Visited[*it]){
St.push(*it);
Visited[*it] = true;
}
}
}while(!St.empty());
}
}
}
void Write(){
ofstream g ("dfs.out");
g << comp << "\n";
g.close();
}
int main(){
Read();
Dfs();
Write();
return 0;
}