Coding style improvements for project_euler problem 45 & 16 (#3087)

* improvements for project euler task 45

* fixed documentation

* update pe_16/sol1.py

* update pe_16/sol2.py

* revert solution changes for sol1

* revert solution changes for sol2

* remove trailing spaces in sol1

* Update sol1.py

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

project_euler/problem_16/sol1.py

@@ -1,11 +1,13 @@
 """
+Problem 16: https://projecteuler.net/problem=16
+
 2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
 
 What is the sum of the digits of the number 2^1000?
 """
 
 
-def solution(power):
+def solution(power: int = 1000) -> int:
     """Returns the sum of the digits of the number 2^power.
     >>> solution(1000)
     1366

project_euler/problem_16/sol2.py

@@ -1,11 +1,13 @@
 """
+Problem 16: https://projecteuler.net/problem=16
+
 2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
 
 What is the sum of the digits of the number 2^1000?
 """
 
 
-def solution(power):
+def solution(power: int = 1000) -> int:
     """Returns the sum of the digits of the number 2^power.
 
     >>> solution(1000)

project_euler/problem_45/sol1.py

@@ -1,4 +1,6 @@
 """
+Problem 45: https://projecteuler.net/problem=45
+
 Triangle, pentagonal, and hexagonal numbers are generated by the following formulae:
 Triangle	 	T(n) = (n * (n + 1)) / 2	 	1, 3, 6, 10, 15, ...
 Pentagonal	 	P(n) = (n * (3 * n − 1)) / 2	 	1, 5, 12, 22, 35, ...
@@ -39,10 +41,10 @@ def is_pentagonal(n: int) -> bool:
     return ((1 + root) / 6) % 1 == 0
 
 
-def compute_num(start: int = 144) -> int:
+def solution(start: int = 144) -> int:
     """
     Returns the next number which is traingular, pentagonal and hexagonal.
-    >>> compute_num(144)
+    >>> solution(144)
     1533776805
     """
     n = start
@@ -54,4 +56,4 @@ def compute_num(start: int = 144) -> int:
 
 
 if __name__ == "__main__":
-    print(f"{compute_num(144)} = ")
+    print(f"{solution()} = ")