Improve Project Euler problem 034 solution 1 (#5165)

project_euler/problem_034/sol1.py

@@ -8,6 +8,8 @@ Note: As 1! = 1 and 2! = 2 are not sums they are not included.
 
 from math import factorial
 
+DIGIT_FACTORIAL = {str(d): factorial(d) for d in range(10)}
+
 
 def sum_of_digit_factorial(n: int) -> int:
     """
@@ -17,7 +19,7 @@ def sum_of_digit_factorial(n: int) -> int:
     >>> sum_of_digit_factorial(0)
     1
     """
-    return sum(factorial(int(char)) for char in str(n))
+    return sum(DIGIT_FACTORIAL[d] for d in str(n))
 
 
 def solution() -> int: