Method add_edge

code/graph/arborescence.cpp:6–7

  vector<vector<pair<ii,int> > > adj;
  arborescence(int _n) : n(_n), uf(n), adj(n) { }
  void add_edge(int a, int b, int c) {
    adj[b].push_back(make_pair(ii(a,b),c)); }
  vii find_min(int r) {
    vi vis(n,-1), mn(n,INF); vii par(n);
    rep(i,0,n) {