algorithms-python/algorithms/tree/bst/count_left_node.py at master · ivan1911/algorithms-python · GitHub

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"""

Write a function count_left_node returns the number of left children in the

tree. For example: the following tree has four left children (the nodes

storing the values 6, 3, 7, and 10):

/ \

6 12

/ \ / \

3 8 10 15

/ \

7 18

count_left_node = 4

"""

import unittest

from bst import Node

from bst import bst

def count_left_node(root):

if root is None:

return 0

elif root.left is None:

return count_left_node(root.right)

else:

return 1 + count_left_node(root.left) + count_left_node(root.right)

"""

The tree is created for testing:

/ \

6 12

/ \ / \

3 8 10 15

/ \

7 18

count_left_node = 4

"""

class TestSuite(unittest.TestCase):

def setUp(self):

self.tree = bst()

self.tree.insert(9)

self.tree.insert(6)

self.tree.insert(12)

self.tree.insert(3)

self.tree.insert(8)

self.tree.insert(10)

self.tree.insert(15)

self.tree.insert(7)

self.tree.insert(18)

def test_count_left_node(self):

self.assertEqual(4, count_left_node(self.tree.root))

if __name__ == '__main__':

unittest.main()

algorithms-python/algorithms/tree/bst/count_left_node.py at master · ivan1911/algorithms-python · GitHub

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