Python/project_euler/problem_03/sol2.py
Bruno Simas Hadlich f438440ac5 Fixes for issue "Fix the LGTM issues #1024" (#1034)
* Added doctest and more explanation about Dijkstra execution.

* tests were not passing with python2 due to missing __init__.py file at number_theory folder

* Removed the dot at the beginning of the imported modules names because 'python3 -m doctest -v data_structures/hashing/*.py' and 'python3 -m doctest -v data_structures/stacks/*.py' were failing not finding hash_table.py and stack.py modules.

* Moved global code to main scope and added doctest for project euler problems 1 to 14.

* Added test case for negative input.

* Changed N variable to do not use end of line scape because in case there is a space after it the script will break making it much more error prone.

* Added problems description and doctests to the ones that were missing. Limited line length to 79 and executed python black over all scripts.

* Changed the way files are loaded to support pytest call.

* Added __init__.py to problems to make them modules and allow pytest execution.

* Added project_euler folder to test units execution

* Changed 'os.path.split(os.path.realpath(__file__))' to 'os.path.dirname()'

* Added Burrows-Wheeler transform algorithm.

* Added changes suggested by cclauss

* Fixes for issue 'Fix the LGTM issues #1024'.

* Added doctest for different parameter types and negative values.

* Fixed doctest issue added at last commit.
2019-07-18 19:05:14 +02:00

64 lines
1.5 KiB
Python

"""
Problem:
The prime factors of 13195 are 5,7,13 and 29. What is the largest prime factor
of a given number N?
e.g. for 10, largest prime factor = 5. For 17, largest prime factor = 17.
"""
from __future__ import print_function, division
try:
raw_input # Python 2
except NameError:
raw_input = input # Python 3
def solution(n):
"""Returns the largest prime factor of a given number n.
>>> solution(13195)
29
>>> solution(10)
5
>>> solution(17)
17
>>> solution(3.4)
3
>>> solution(0)
Traceback (most recent call last):
...
ValueError: Parameter n must be greater or equal to one.
>>> solution(-17)
Traceback (most recent call last):
...
ValueError: Parameter n must be greater or equal to one.
>>> solution([])
Traceback (most recent call last):
...
TypeError: Parameter n must be int or passive of cast to int.
>>> solution("asd")
Traceback (most recent call last):
...
TypeError: Parameter n must be int or passive of cast to int.
"""
try:
n = int(n)
except (TypeError, ValueError) as e:
raise TypeError("Parameter n must be int or passive of cast to int.")
if n <= 0:
raise ValueError("Parameter n must be greater or equal to one.")
prime = 1
i = 2
while i * i <= n:
while n % i == 0:
prime = i
n //= i
i += 1
if n > 1:
prime = n
return int(prime)
if __name__ == "__main__":
print(solution(int(raw_input().strip())))