Meet your coaches
Talk through the problem while you code. Signed-in reps become prep memory for the next session.
Start Part 1 to unlock your next challenge
Lowest Common Ancestor of a Binary Tree
This is really about exploring a state space without revisiting the same work. Interviewers love it because it reveals your traversal modeling and your edge-case discipline. Be clear about what a state is; that's the difference between BFS/DFS working or blowing up.
Learn this pattern
Graph Interview Questions
BFS explores by layers using a queue; DFS explores deeply using a stack or recursion -- the same traversal with a different container. Choose BFS for shortest-path in unweighted graphs and "minimum steps," DFS for counting components, islands, and tree recursion.
Meet your coaches
Talk through the problem while you code. Signed-in reps become prep memory for the next session.
Chat with Fin or Coco right now on mobile.
Start talking through the problem here. Switch to desktop when you're ready to code and run tests.
Start coaching sessionStart a coached rep now. Sign in before or after the session so StrongYes can save what you struggled with to your prep memory.
Email me this coached-rep link
Start Part 1 to unlock your next challenge
Desktop required
Sorry - mobile cannot run the editor and tests yet. Use the next step below or email yourself a link to continue on desktop.
Graph Interview Questions gives you a useful next rep while you are still on your phone.