[Project Euler] Fix code style for problems 15 and 34 (#3076)

* Add type hints and default args to problem 15

* Changes function's name to solution in problem 34

* Update sol1.py

* Update sol1.py

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

project_euler/problem_34/sol1.py

@@ -1,4 +1,6 @@
 """
+Problem 34: https://projecteuler.net/problem=34
+
 145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145.
 Find the sum of all numbers which are equal to the sum of the factorial of their digits.
 Note: As 1! = 1 and 2! = 2 are not sums they are not included.
@@ -18,12 +20,12 @@ def sum_of_digit_factorial(n: int) -> int:
     return sum(factorial(int(char)) for char in str(n))
 
 
-def compute() -> int:
+def solution() -> int:
     """
     Returns the sum of all numbers whose
     sum of the factorials of all digits
     add up to the number itself.
-    >>> compute()
+    >>> solution()
     40730
     """
     limit = 7 * factorial(9) + 1
@@ -31,4 +33,4 @@ def compute() -> int:
 
 
 if __name__ == "__main__":
-    print(f"{compute()} = ")
+    print(f"{solution()} = ")