Created problem_34 in project_euler

project_euler/problem_34/sol1.py

@@ -9,15 +9,33 @@
 
 
 def factorial(n: int) -> int:
-    """
-    Returns the factorial of n
+    """Return the factorial of n.
+
     >>> factorial(5)
     120
     >>> factorial(1)
     1
     >>> factorial(0)
-    1
+    0
+    >>> factorial(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: n must be >= 0
+
+    >>> factorial(1.1)
+    Traceback (most recent call last):
+        ...
+    ValueError: n must be exact integer
     """
+
+    import math
+
+    if not n >= 0:
+        raise ValueError("n must be >= 0")
+    if math.floor(n) != n:
+        raise ValueError("n must be exact integer")
+    if n + 1 == n:  # catch a value like 1e300
+        raise OverflowError("n too large")
     result = 1
     factor = 2
     while factor <= n:
@@ -27,7 +45,7 @@ def factorial(n: int) -> int:
 
 
 def sum_of_digit_factorial(n: int) -> int:
-    """
+    """ 
     Returns the sum of the digits in n
     >>> sum_of_digit_factorial(15)
     121
@@ -41,17 +59,17 @@ def sum_of_digit_factorial(n: int) -> int:
 
 def compute() -> int:
     """
-    Returns the sum of all numbers whose
+    Returns the sum of all numbers whose 
     sum of the factorials of all digits
     add up to the number itself.
     >>> compute()
     40730
     """
-    summ = 0
+    the_list = []
     for num in range(3, 7 * factorial(9) + 1):
         if sum_of_digit_factorial(num) == num:
-            summ += num
-    return summ
+            the_list.append(num)
+    return sum(the_list)
 
 
 if __name__ == "__main__":