Python/project_euler/problem_02/sol3.py
Edward Nuno f36a2f621e
Hacktoberfest 2020: Apply style guidelines for Project Euler problem_02 (#2898)
* Fix typehints in project_euler/problem01

Squashed commit of the following:

commit 6801d073b31bf702814861cd3b07b634ca295bfa
Author: Archaengel <god11341258@gmail.com>
Date:   Mon Oct 5 16:40:10 2020 -0700

    Fix typehints in project_euler/problem01

commit 29afc3af114abd1b99dc3f7c8fc99128229db131
Author: Archaengel <god11341258@gmail.com>
Date:   Mon Oct 5 15:06:34 2020 -0700

    Add typehints and default argument for project_euler/problem_01

* Add default args, typehints, and expand variable names for PE prob 02
2020-10-06 10:04:16 +05:30

42 lines
868 B
Python

"""
Problem:
Each new term in the Fibonacci sequence is generated by adding the previous
two terms. By starting with 1 and 2, the first 10 terms will be:
1,2,3,5,8,13,21,34,55,89,..
By considering the terms in the Fibonacci sequence whose values do not exceed
n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
10.
"""
def solution(n: int = 4000000) -> int:
"""Returns the sum of all fibonacci sequence even elements that are lower
or equals to n.
>>> solution(10)
10
>>> solution(15)
10
>>> solution(2)
2
>>> solution(1)
0
>>> solution(34)
44
"""
if n <= 1:
return 0
a = 0
b = 2
count = 0
while 4 * b + a <= n:
a, b = b, 4 * b + a
count += a
return count + b
if __name__ == "__main__":
print(solution(int(input().strip())))