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

# Challenge Notebook¶

## Constraints¶

• Do we just want to calculate the cost and not list the actual order of operations?
• Yes
• Can we assume the inputs are valid?
• No
• Can we assume this fits memory?
• Yes

## Test Cases¶

• None -> Exception
• [] -> 0
• [Matrix(2, 3), Matrix(3, 6), Matrix(6, 4), Matrix(4, 5)] -> 124

## 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 [ ]:
class Matrix(object):

def __init__(self, first, second):
self.first = first
self.second = second

In [ ]:
class MatrixMultiplicationCost(object):

def find_min_cost(self, matrices):
# TODO: Implement me
pass


## Unit Test¶

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

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

class TestMatrixMultiplicationCost(unittest.TestCase):

def test_find_min_cost(self):
matrix_mult_cost = MatrixMultiplicationCost()
self.assertRaises(TypeError, matrix_mult_cost.find_min_cost, None)
self.assertEqual(matrix_mult_cost.find_min_cost([]), 0)
matrices = [Matrix(2, 3),
Matrix(3, 6),
Matrix(6, 4),
Matrix(4, 5)]
expected_cost = 124
self.assertEqual(matrix_mult_cost.find_min_cost(matrices), expected_cost)
print('Success: test_find_min_cost')

def main():
test = TestMatrixMultiplicationCost()
test.test_find_min_cost()

if __name__ == '__main__':
main()


## Solution Notebook¶

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