Python/project_euler/problem_06/sol4.py
Du Yuanchao 2de2267319
Updated problem_06 in Project Euler (#2439)
* * rename variable
* fix type hint
* fix doctest

* added test function

* fixed import error

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-09-17 11:37:53 +02:00

43 lines
1.0 KiB
Python
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

"""
Problem:
The sum of the squares of the first ten natural numbers is,
1^2 + 2^2 + ... + 10^2 = 385
The square of the sum of the first ten natural numbers is,
(1 + 2 + ... + 10)^2 = 552 = 3025
Hence the difference between the sum of the squares of the first ten natural
numbers and the square of the sum is 3025 385 = 2640.
Find the difference between the sum of the squares of the first N natural
numbers and the square of the sum.
"""
def solution(n: int) -> int:
"""Returns the difference between the sum of the squares of the first n
natural numbers and the square of the sum.
>>> solution(10)
2640
>>> solution(15)
13160
>>> solution(20)
41230
>>> solution(50)
1582700
>>> solution(100)
25164150
"""
sum_of_squares = n * (n + 1) * (2 * n + 1) / 6
square_of_sum = (n * (n + 1) / 2) ** 2
return int(square_of_sum - sum_of_squares)
if __name__ == "__main__":
import doctest
doctest.testmod()
print(solution(int(input("Enter a number: ").strip())))