Breadth first order — practice exercise

What you'll be asked to do

1. 1.Breadth first orderexercise · easy · 10 min

   Walk the graph breadth first and join the nodes visited.

   Passes when: #out should show a-b-c-d.

2. 2.Depth first orderexercise · easy · 10 min · practice plan

   Walk depth first with recursion and join the nodes visited.

   Passes when: #out should show a-b-d-c.

3. 3.Count the reachableexercise · easy · 10 min · practice plan

   Count how many nodes can be reached from a.

   Passes when: #out should show four reachable.

4. 4.Shortest hop countexercise · easy · 10 min · practice plan

   Report the fewest edges from a to d.

   Passes when: #out should show hops 2.

5. 5.Unreachable nodeexercise · medium · 10 min · practice plan

   Report that an isolated node cannot be reached.

   Passes when: #out should show unreachable.

6. 6.Fix the traversal without a visited setbug fix · easy · 8 min

   Revisiting nodes repeats them, so a guard caps the walk here.

   Passes when: #out should show visited 3.

7. 7.Fix BFS using a stackbug fix · medium · 8 min · practice plan

   Popping from the back makes the walk depth first, so the order changes.

   Passes when: #out should show a-b-c-d.

8. 8.Fix the node marked after dequeuebug fix · easy · 8 min · practice plan

   Marking on removal lets a node be queued twice before it is seen.

   Passes when: #out should show four reachable.

9. 9.Fix the distance overwrittenbug fix · easy · 8 min · practice plan

   Updating a distance already set replaces the shortest with a longer one.

   Passes when: #out should show hops 2.

10. 10.Fix the isolated node countedbug fix · easy · 8 min · practice plan

    A node present in the map is not necessarily reachable.

    Passes when: #out should show unreachable.

Between them these tasks cover Visited sets, Queue vs stack and Shortest hops.

Looking for a different chapter? See every practice set, or switch to the interview theory questions.