24 lines
1.1 KiB
Python
24 lines
1.1 KiB
Python
def hex_key(num):
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"""You have been tasked to write a function that receives
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a hexadecimal number as a string and counts the number of hexadecimal
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digits that are primes (prime number, or a prime, is a natural number
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greater than 1 that is not a product of two smaller natural numbers).
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Hexadecimal digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.
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Prime numbers are 2, 3, 5, 7, 11, 13, 17,...
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So you have to determine a number of the following digits: 2, 3, 5, 7,
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B (=decimal 11), D (=decimal 13).
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Note: you may assume the input is always correct or empty string,
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and symbols A,B,C,D,E,F are always uppercase.
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Examples:
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For num = "AB" the output should be 1.
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For num = "1077E" the output should be 2.
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For num = "ABED1A33" the output should be 4.
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For num = "123456789ABCDEF0" the output should be 6.
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For num = "2020" the output should be 2.
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"""
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prime_hex_digits = {'2', '3', '5', '7', 'B', 'D'}
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count = 0
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for digit in num:
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if digit in prime_hex_digits:
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count += 1
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return count |