void tarjanSCC(int u) {
dfs_low[u] = dfs_num[u] = dfsNumberCounter++; // dfs_low[u] <= dfs_num[u]
S.push_back(u); // stores u in a vector based on order of visitation
visited[u] = 1;
for (int j = 0; j < (int)AdjList[u].size(); j++) {
ii v = AdjList[u][j];
if (dfs_num[v.first] == 0)
tarjanSCC(v.first);
if (visited[v.first])
dfs_low[u] = min(dfs_low[u], dfs_low[v.first]); }
if (dfs_low[u] == dfs_num[u]) { // if this is a root (start) of an SCC
scc.push_back(vi());
while (1) {
int v = S.back(); S.pop_back(); visited[v] = 0;
scc.back().push_back(v);
node_to_scc_num[v] = scc_num;
if (u == v) break; }
scc_num++;
}
}
vi &get_array() { return P.back(); }
