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Strassen matrix multiply #13470

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Describe your change:

  • Add an algorithm?
  • Fix a bug or typo in an existing algorithm?
  • Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
  • Documentation change?

Checklist:

  • I have read CONTRIBUTING.md.
  • This pull request is all my own work -- I have not plagiarized.
  • I know that pull requests will not be merged if they fail the automated tests.
  • This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
  • All new Python files are placed inside an existing directory.
  • All filenames are in all lowercase characters with no spaces or dashes.
  • All functions and variable names follow Python naming conventions.
  • All function parameters and return values are annotated with Python type hints.
  • All functions have doctests that pass the automated testing.
  • All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
  • If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

@algorithms-keeper algorithms-keeper bot added require descriptive names This PR needs descriptive function and/or variable names require tests Tests [doctest/unittest/pytest] are required labels Oct 13, 2025
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Click here to look at the relevant links ⬇️

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matrix/strassen_matrix_multiply.py Outdated

Matrix = List[List[int]]

def add(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function add

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py Outdated
n = len(A)
return [[A[i][j] + B[i][j] for j in range(n)] for i in range(n)]

def sub(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function sub

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py Outdated
n = len(A)
return [[A[i][j] - B[i][j] for j in range(n)] for i in range(n)]

def naive_mul(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function naive_mul

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py
ci[j] += a_ik * bk[j]
return C

def next_power_of_two(n: int) -> int:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function next_power_of_two

Please provide descriptive name for the parameter: n

matrix/strassen_matrix_multiply.py Outdated
p <<= 1
return p

def pad_matrix(A: Matrix, size: int) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function pad_matrix

Please provide descriptive name for the parameter: A

matrix/strassen_matrix_multiply.py Outdated

m = next_power_of_two(n_orig)
if m != n_orig:
A_pad = pad_matrix(A, m)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: A_pad

matrix/strassen_matrix_multiply.py Outdated
m = next_power_of_two(n_orig)
if m != n_orig:
A_pad = pad_matrix(A, m)
B_pad = pad_matrix(B, m)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: B_pad

matrix/strassen_matrix_multiply.py Outdated
A_pad = pad_matrix(A, m)
B_pad = pad_matrix(B, m)
else:
A_pad, B_pad = A, B
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: A_pad

Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: B_pad

matrix/strassen_matrix_multiply.py Outdated
else:
A_pad, B_pad = A, B

C_pad = _strassen_recursive(A_pad, B_pad, threshold)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: C_pad

matrix/strassen_matrix_multiply.py Outdated
C = unpad_matrix(C_pad, n_orig, n_orig)
return C

def _strassen_recursive(A: Matrix, B: Matrix, threshold: int) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function _strassen_recursive

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

@algorithms-keeper algorithms-keeper bot added the awaiting reviews This PR is ready to be reviewed label Oct 13, 2025
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algorithms-keeper bot reviewed Oct 13, 2025
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Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Python:

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.
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algorithms-keeper actions can be triggered by commenting on this PR:

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  • @algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

matrix/strassen_matrix_multiply.py
https://en.wikipedia.org/wiki/Strassen_algorithm
"""

Matrix = list[list[int]]
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: Matrix

matrix/strassen_matrix_multiply.py Outdated

Matrix = list[list[int]]

def add(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function add

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py Outdated
return [[A[i][j] + B[i][j] for j in range(n)] for i in range(n)]


def sub(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function sub

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py Outdated
return [[A[i][j] - B[i][j] for j in range(n)] for i in range(n)]


def naive_mul(A: Matrix, B: Matrix) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function naive_mul

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

matrix/strassen_matrix_multiply.py
return C


def next_power_of_two(n: int) -> int:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function next_power_of_two

Please provide descriptive name for the parameter: n

matrix/strassen_matrix_multiply.py Outdated
return []

if (m := next_power_of_two(n_orig)) != n_orig:
A_pad = pad_matrix(A, m)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: A_pad

matrix/strassen_matrix_multiply.py Outdated

if (m := next_power_of_two(n_orig)) != n_orig:
A_pad = pad_matrix(A, m)
B_pad = pad_matrix(B, m)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: B_pad

matrix/strassen_matrix_multiply.py Outdated
A_pad = pad_matrix(A, m)
B_pad = pad_matrix(B, m)
else:
A_pad, B_pad = A, B
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: A_pad

Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: B_pad

matrix/strassen_matrix_multiply.py Outdated
else:
A_pad, B_pad = A, B

C_pad = _strassen_recursive(A_pad, B_pad, threshold)
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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: C_pad

matrix/strassen_matrix_multiply.py Outdated
return C


def _strassen_recursive(A: Matrix, B: Matrix, threshold: int) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function _strassen_recursive

Please provide descriptive name for the parameter: A

Please provide descriptive name for the parameter: B

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algorithms-keeper bot reviewed Oct 13, 2025
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Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Python:

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.
algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

  • @algorithms-keeper review to trigger the checks for only added pull request files
  • @algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

matrix/strassen_matrix_multiply.py
https://en.wikipedia.org/wiki/Strassen_algorithm
"""

Matrix = list[list[int]]
Copy link

Choose a reason for hiding this comment

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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: Matrix

matrix/strassen_matrix_multiply.py
return result


def next_power_of_two(n: int) -> int:
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Please provide descriptive name for the parameter: n

matrix/strassen_matrix_multiply.py
return unpad_matrix(c_pad, n_orig, n_orig)


def _strassen_recursive(matrix_a: Matrix, matrix_b: Matrix, threshold: int) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function _strassen_recursive

@algorithms-keeper algorithms-keeper bot added the tests are failing Do not merge until tests pass label Oct 13, 2025
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algorithms-keeper bot reviewed Oct 13, 2025
View reviewed changes
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Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Python:

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.
algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

  • @algorithms-keeper review to trigger the checks for only added pull request files
  • @algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

matrix/strassen_matrix_multiply.py
https://en.wikipedia.org/wiki/Strassen_algorithm
"""

Matrix = list[list[int]]
Copy link

Choose a reason for hiding this comment

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Variable and function names should follow the snake_case naming convention. Please update the following name accordingly: Matrix

matrix/strassen_matrix_multiply.py
return result


def next_power_of_two(n: int) -> int:
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Please provide descriptive name for the parameter: n

matrix/strassen_matrix_multiply.py
return unpad_matrix(c_pad, n_orig, n_orig)


def _strassen_recursive(matrix_a: Matrix, matrix_b: Matrix, threshold: int) -> Matrix:
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As there is no test file in this pull request nor any test function or class in the file matrix/strassen_matrix_multiply.py, please provide doctest for the function _strassen_recursive

@algorithms-keeper algorithms-keeper bot removed the tests are failing Do not merge until tests pass label Oct 13, 2025
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cclauss commented Oct 14, 2025

Closing require_descriptive_names PRs to prepare for Hacktoberfest

@cclauss cclauss closed this Oct 14, 2025
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