[Project Euler] Fix code style in Problem 41 (TheAlgorithms#2992)

* add problem title and link, fix f-string

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* fix code style and improve doctests

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* undo changes to the main call

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* remove assignment operator in f-string

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* add newline after first import to attempt to fix pre-commit workflow

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* undo doctest changes, rename compute_pandigital_primes to solution

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* update solution to return the actual solution instead of a list

Signed-off-by: joan.rosellr <joan.rosellr@gmail.com>

* Update sol1.py

Co-authored-by: Dhruv <dhruvmanila@gmail.com>

Author: jrosellr

project_euler/problem_41/sol1.py

@@ -1,19 +1,19 @@
-from __future__ import annotations
-
-from itertools import permutations
-from math import sqrt
-
 """
+Pandigital prime
+Problem 41: https://projecteuler.net/problem=41
+
 We shall say that an n-digit number is pandigital if it makes use of all the digits
 1 to n exactly once. For example, 2143 is a 4-digit pandigital and is also prime.
 What is the largest n-digit pandigital prime that exists?
-"""
 
-"""
 All pandigital numbers except for 1, 4 ,7 pandigital numbers are divisible by 3.
-So we will check only 7 digit panddigital numbers to obtain the largest possible
+So we will check only 7 digit pandigital numbers to obtain the largest possible
 pandigital prime.
 """
+from __future__ import annotations
+
+from itertools import permutations
+from math import sqrt
 
 
 def is_prime(n: int) -> bool:
@@ -35,20 +35,22 @@ def is_prime(n: int) -> bool:
     return True
 
 
-def compute_pandigital_primes(n: int) -> list[int]:
+def solution(n: int = 7) -> int:
     """
-    Returns a list of all n-digit pandigital primes.
-    >>> compute_pandigital_primes(2)
-    []
-    >>> max(compute_pandigital_primes(4))
+    Returns the maximum pandigital prime number of length n.
+    If there are none, then it will return 0.
+    >>> solution(2)
+    0
+    >>> solution(4)
     4231
-    >>> max(compute_pandigital_primes(7))
+    >>> solution(7)
     7652413
     """
     pandigital_str = "".join(str(i) for i in range(1, n + 1))
     perm_list = [int("".join(i)) for i in permutations(pandigital_str, n)]
-    return [num for num in perm_list if is_prime(num)]
+    pandigitals = [num for num in perm_list if is_prime(num)]
+    return max(pandigitals) if pandigitals else 0
 
 
 if __name__ == "__main__":
-    print(f"{max(compute_pandigital_primes(7)) = }")
+    print(f"{solution() = }")