Articulation Points
A vertex is an articulation point when some DFS child has low[v] >= disc[u], or it is the root with two subtrees.
Decision · step 5 of 19Bridges and Components: Articulation points
Edge 2-0 leads to a vertex seen at time 0, an ancestor on the current path. That is earlier than low[2] = 2, so low[2] becomes 0: 2 can climb to 0.
What you will see
Cut vertices are marked as the low-link values arrive.
Cost
| Best | O(V + E) |
|---|---|
| Average | O(V + E) |
| Worst | O(V + E) |
| Space | O(V) |
How you work with it here
play it through, step one change at a time, scrub to any step, run it on your own input, predict what happens next.
Screen readers: Vertices announce name, discovery numbers where relevant and component; each step announces the structural conclusion (bridge found, component closed).
Reduced motion: Component colouring and ordering changes crossfade in place.
Before this
Taught by the same lesson
Bridges and Components covers these too, in the same run.