1. Alyce Brady CS 470: Data Structures CS 510: Computer Algorithms
Breadth-First
Binary Tree
Traversal Algorithm
Alyce Brady
CS 470: Data Structures
CS 510: Computer Algorithms

2. Reminder: Breadth-First TraversalC D E F G
A B C D E F G

3. Pseudo-Code for Breadth-First Traversal
put root node onto a queue
while the queue is not empty
dequeue the next node
visit the node e.g., print value
enqueue the left child node
enqueue the right child node

4. Breadth-First Search
Queue: A B C
Current: D E F G
A B C D E F G

5. Breadth-First Search
Queue: A A B C
Current: D E F G

6. Breadth-First Search
Queue: A A B C
Current: D E F G A

7. Breadth-First Search
Queue: A B C
Current: D E F G A A

8. Breadth-First Search
Queue: A B B C
Current: D E F G A A

9. Breadth-First Search
Queue: A C B B C
Current: D E F G A A

10. Breadth-First Search
Queue: A C B B C
Current: D E F G B A

11. Breadth-First Search
Queue: A C B C
Current: D E F G B
A B

12. Breadth-First Search
Queue: A D C B C
Current: D E F G B
A B

13. Breadth-First Search
Queue: A E D C B C
Current: D E F G B
A B

14. Breadth-First Search
Queue: A E D C B C
Current: D E F G C
A B

15. Breadth-First Search
Queue: A E D B C
Current: D E F G C
A B C

16. Breadth-First Search
Queue: A F E D B C
Current: D E F G C
A B C

17. Breadth-First Search
Queue: A G F E D B C D E F G
Current: C
A B C

18. Breadth-First Search
Queue: A G F E D B C D E F G
Current: D
A B C

19. Breadth-First Search
Queue: A G F E B C D E F G
Current: D
A B C D

20. Breadth-First Search
Queue: A G F E B C D E F G
Current: E
A B C D

21. Breadth-First Search
Queue: A G F B C D E F G
Current: E
A B C D E

22. Breadth-First Search
Queue: A G F B C D E F G
Current: F
A B C D E

23. Breadth-First Search
Queue: A G B C D E F G
Current: F
A B C D E F

24. Breadth-First Search
Queue: A G B C D E F G
Current: G
A B C D E F

25. Breadth-First Search
Queue: A B C D E F G
Current: G
A B C D E F G

26. Breadth-First Search A B C D E F G
A B C D E F G

27. Time and Space Complexity for Breadth-First Search Alg.
Time Complexity
Consider each node twice O(n)
when put on queue
when taken from queue

28. Time and Space Complexity for Breadth-First Search Alg.
Queue to handle unexplored nodes
Queue length = width of lowest level (n/2)
O(n)