private void dfs(Digraph G, int v) { marked[v] = true; preorder[v] = pre++; stack1.push(v); stack2.push(v); for (int w : G.adj(v)) { if (!marked[w]) dfs(G, w); else if (id[w] == -1) { while (preorder[stack2.peek()] > preorder[w]) stack2.pop(); } } // found strong component containing v if (stack2.peek() == v) { stack2.pop(); int w; do { w = stack1.pop(); id[w] = count; } while (w != v); count++; } }