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Fix binomial distribution overflow for large trial counts - #15662

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harshkanhat wants to merge 3 commits into
TheAlgorithms:masterfrom
harshkanhat:fix-binomial-overflow
Open

harshkanhat wants to merge 3 commits into
TheAlgorithms:masterfrom
harshkanhat:fix-binomial-overflow

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@harshkanhat

@harshkanhat harshkanhat commented Oct 28, 2026 •

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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?

My changes

Replaced the factorial-based binomial coefficient calculation with Python's math.comb() to prevent the overflow error that occurs with large trial counts.
Added a regression test for 171 trials to verify that the binomial distribution returns the expected probability.
Fixes #15656

Testing

  • Ran py -m pytest maths/test_binomial_distribution.py -v
  • Result: 1 passed

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 binomial_distribution overflows at 171 trials even when the result is representable #15656 ".

@algorithms-keeper algorithms-keeper Bot added awaiting reviews This PR is ready to be reviewed enhancement This PR modified some existing files labels Oct 28, 2026
@algorithms-keeper algorithms-keeper Bot added the tests are failing Do not merge until tests pass label Oct 28, 2026
@algorithms-keeper algorithms-keeper Bot removed the tests are failing Do not merge until tests pass label Oct 28, 2026

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binomial_distribution overflows at 171 trials even when the result is representable

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