Remove type cast in combinations algorithm (#7607)

* Remove commented-out print statements in algorithmic functions

* Encapsulate non-algorithmic code in __main__

* Remove unused print_matrix function

* Remove print statement in __init__

* Remove print statement from doctest

* Encapsulate non-algorithmic code in __main__

* Modify algorithm to return instead of print

* Encapsulate non-algorithmic code in __main__

* Refactor data_safety_checker to return instead of print

* updating DIRECTORY.md

* updating DIRECTORY.md

* Apply suggestions from code review

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* updating DIRECTORY.md

* Remove int cast and change float division to int division

* Move new-line chars

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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Tianyi Zheng 2022-10-25 16:34:46 -04:00 committed by GitHub
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@ -35,18 +35,18 @@ def combinations(n: int, k: int) -> int:
# to calculate a factorial of a negative number, which is not possible # to calculate a factorial of a negative number, which is not possible
if n < k or k < 0: if n < k or k < 0:
raise ValueError("Please enter positive integers for n and k where n >= k") raise ValueError("Please enter positive integers for n and k where n >= k")
return int(factorial(n) / ((factorial(k)) * (factorial(n - k)))) return factorial(n) // (factorial(k) * factorial(n - k))
if __name__ == "__main__": if __name__ == "__main__":
print( print(
"\nThe number of five-card hands possible from a standard", "The number of five-card hands possible from a standard",
f"fifty-two card deck is: {combinations(52, 5)}", f"fifty-two card deck is: {combinations(52, 5)}\n",
) )
print( print(
"\nIf a class of 40 students must be arranged into groups of", "If a class of 40 students must be arranged into groups of",
f"4 for group projects, there are {combinations(40, 4)} ways", f"4 for group projects, there are {combinations(40, 4)} ways",
"to arrange them.\n", "to arrange them.\n",
) )
@ -54,5 +54,5 @@ if __name__ == "__main__":
print( print(
"If 10 teams are competing in a Formula One race, there", "If 10 teams are competing in a Formula One race, there",
f"are {combinations(10, 3)} ways that first, second and", f"are {combinations(10, 3)} ways that first, second and",
"third place can be awarded.\n", "third place can be awarded.",
) )