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35 lines
1.1 KiB
Python
35 lines
1.1 KiB
Python
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"""
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== Perfect Number ==
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In number theory, a perfect number is a positive integer that is equal to the sum of
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its positive divisors, excluding the number itself.
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For example: 6 ==> divisors[1, 2, 3, 6]
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Excluding 6, the sum(divisors) is 1 + 2 + 3 = 6
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So, 6 is a Perfect Number
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Other examples of Perfect Numbers: 28, 486, ...
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https://en.wikipedia.org/wiki/Perfect_number
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"""
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def perfect(number: int) -> bool:
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"""
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>>> perfect(27)
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False
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>>> perfect(28)
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True
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>>> perfect(29)
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False
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Start from 1 because dividing by 0 will raise ZeroDivisionError.
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A number at most can be divisible by the half of the number except the number
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itself. For example, 6 is at most can be divisible by 3 except by 6 itself.
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"""
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return sum(i for i in range(1, ((number // 2) + 1)) if number % i == 0) == number
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if __name__ == "__main__":
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print("Program to check whether a number is a Perfect number or not.......")
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number = int(input("Enter number: ").strip())
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print(f"{number} is {'' if perfect(number) else 'not '} a Perfect Number.")
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