This notebook was prepared by Donne Martin. Source and license info is on GitHub.

Challenge Notebook

Problem: Implement breadth-first traversal on a binary tree.

Constraints

  • Can we assume we already have a Node class with an insert method?
    • Yes
  • Can we assume this fits in memory?
    • Yes
  • What should we do with each node when we process it?
    • Call an input method visit_func on the node

Test Cases

Breadth-First Traversal

  • 5, 2, 8, 1, 3 -> 5, 2, 8, 1, 3

Algorithm

Refer to the Solution Notebook. If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start.

Code

In [ ]:
%run ../bst/bst.py
%load ../bst/bst.py
In [ ]:
class BstBfs(Bst):

    def bfs(self, visit_func):
        # TODO: Implement me
        pass

Unit Test

In [ ]:
%run ../utils/results.py
In [ ]:
# %load test_bfs.py
import unittest


class TestBfs(unittest.TestCase):

    def __init__(self, *args, **kwargs):
        super(TestBfs, self).__init__()
        self.results = Results()

    def test_bfs(self):
        bst = BstBfs(Node(5))
        bst.insert(2)
        bst.insert(8)
        bst.insert(1)
        bst.insert(3)
        bst.bfs(self.results.add_result)
        self.assertEqual(str(self.results), '[5, 2, 8, 1, 3]')

        print('Success: test_bfs')


def main():
    test = TestBfs()
    test.test_bfs()


if __name__ == '__main__':
    main()

Solution Notebook

Review the Solution Notebook for a discussion on algorithms and code solutions.