Python/project_euler/problem_007/sol1.py
Michael D 98e9d6bdb6
Fix style of the first ten solutions for Project Euler (#3242)
* Fix style of the first ten solutions for Project Euler

- Unify the header docstring, and add reference URLs to wikipedia
  or similar
- Fix docstrings to be properly multilined
- Add newlines where appropriate
- Add doctests where they were missing
- Remove doctests that test for the correct solution
- fix obvious spelling or grammar mistakes in comments and
  exception messages
- Fix line endings to be UNIX. This makes two of the files seem
  to have changed completely
- no functional changes in any of the solutions were done
  (except for the spelling fixes mentioned above)

* Fix docstrings and main function as per Style Guide
2020-10-25 08:53:16 +05:30

77 lines
1.3 KiB
Python

"""
Project Euler Problem 7: https://projecteuler.net/problem=7
10001st prime
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we
can see that the 6th prime is 13.
What is the 10001st prime number?
References:
- https://en.wikipedia.org/wiki/Prime_number
"""
from math import sqrt
def is_prime(num: int) -> bool:
"""
Determines whether the given number is prime or not
>>> is_prime(2)
True
>>> is_prime(15)
False
>>> is_prime(29)
True
>>> is_prime(0)
False
"""
if num == 2:
return True
elif num % 2 == 0:
return False
else:
sq = int(sqrt(num)) + 1
for i in range(3, sq, 2):
if num % i == 0:
return False
return True
def solution(nth: int = 10001) -> int:
"""
Returns the n-th prime number.
>>> solution(6)
13
>>> solution(1)
2
>>> solution(3)
5
>>> solution(20)
71
>>> solution(50)
229
>>> solution(100)
541
"""
count = 0
number = 1
while count != nth and number < 3:
number += 1
if is_prime(number):
count += 1
while count != nth:
number += 2
if is_prime(number):
count += 1
return number
if __name__ == "__main__":
print(f"{solution() = }")