Timus- 1106. Two Teams

1106.cpp

#include <iostream>
#include <vector>
using namespace std;

int main()
{   
    int n, t, tt;
    cin >> n;
    vector< int > friends[n + 1];
    for(int i = 1; i <= n; i++){
        while(cin >> t){
            if(t) friends[i].push_back(t);
            else break;
        }
    }
    int st[n + 1] = {0};
    for(int i = 1; i <= n; i++){
        if(st[i] == 0){
            st[i] = 1;
            for(int x: friends[i])
                if(st[x] == 0)
                   st[x] = 2;
        }
        
    }
    int ans = 0;
    for(int i = 1; i <= n; i++){
        if(st[i] == 1){
            ans++;
        }
    }
    cout << ans << '\n';
    for(int i = 1; i <= n; i++)
        if(st[i] == 1) 
            cout << i << ' ';

    return 0;
}