Python: Function to determine if number is square, cube, etc

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Chapters
00:00 Question
01:04 Accepted answer (Score 8)
01:37 Thank you

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Full question
https://stackoverflow.com/questions/4535...

Accepted answer links:
[Is floating point math broken?]: https://stackoverflow.com/questions/5880...

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https://meta.stackexchange.com/help/lice...

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Tags
#python #algorithm #function #math #division

#avk47

ACCEPTED ANSWER

Score 8

Floating point arithmetic is not exact--see Is floating point math broken?.

So check your answer using exact-integer math. Round r to the nearest integer then see if the power works. This Python 3 code removes some of your redundant type-casting. For Python 2, wrap the calculation of r into an int() typecast (which is not needed for Python 3).

def is_power(N, n):
    r = round(N ** (1.0 / n))
    return r**n == N