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

# Challenge Notebook¶

## Constraints¶

• Is a balanced tree one where the heights of two sub trees of any node doesn't differ by more than 1?
• Yes
• If this is called on a None input, should we raise an exception?
• Yes
• Can we assume we already have a Node class with an insert method?
• Yes
• Can we assume this fits memory?
• Yes

## Test Cases¶

• None -> No
• 1 -> Yes
• 5, 3, 8, 1, 4 -> Yes
• 5, 3, 8, 9, 10 -> No

## 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

In [ ]:
class BstBalance(Bst):

def check_balance(self):
# TODO: Implement me
pass


## Unit Test¶

The following unit test is expected to fail until you solve the challenge.

In [ ]:
# %load test_check_balance.py
import unittest

class TestCheckBalance(unittest.TestCase):

def test_check_balance_empty(self):
bst = BstBalance(None)
bst.check_balance()

def test_check_balance(self):
bst = BstBalance(Node(5))
self.assertEqual(bst.check_balance(), True)

bst.insert(3)
bst.insert(8)
bst.insert(1)
bst.insert(4)
self.assertEqual(bst.check_balance(), True)

bst = BstBalance(Node(5))
bst.insert(3)
bst.insert(8)
bst.insert(9)
bst.insert(10)
self.assertEqual(bst.check_balance(), False)

bst = BstBalance(Node(3))
bst.insert(2)
bst.insert(1)
bst.insert(5)
bst.insert(4)
bst.insert(6)
bst.insert(7)
self.assertEqual(bst.check_balance(), True)

print('Success: test_check_balance')

def main():
test = TestCheckBalance()
test.assertRaises(TypeError, test.test_check_balance_empty)
test.test_check_balance()

if __name__ == '__main__':
main()


## Solution Notebook¶

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