Python/project_euler/problem_20/sol1.py

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"""
Problem 20: https://projecteuler.net/problem=20
n! means n × (n 1) × ... × 3 × 2 × 1
For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
Find the sum of the digits in the number 100!
"""
def factorial(num: int) -> int:
"""Find the factorial of a given number n"""
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fact = 1
for i in range(1, num + 1):
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fact *= i
return fact
def split_and_add(number: int) -> int:
"""Split number digits and add them."""
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sum_of_digits = 0
while number > 0:
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last_digit = number % 10
sum_of_digits += last_digit
number = number // 10 # Removing the last_digit from the given number
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return sum_of_digits
def solution(num: int = 100) -> int:
"""Returns the sum of the digits in the factorial of num
>>> solution(100)
648
>>> solution(50)
216
>>> solution(10)
27
>>> solution(5)
3
>>> solution(3)
6
>>> solution(2)
2
>>> solution(1)
1
"""
nfact = factorial(num)
result = split_and_add(nfact)
return result
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if __name__ == "__main__":
print(solution(int(input("Enter the Number: ").strip())))