old_contents: """
  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.
  """
  
  from math import factorial
  
  
  def sum_of_digit_factorial(n: int) -> int:
      """
      Returns the sum of the factorial of digits in n
      >>> sum_of_digit_factorial(15)
      121
      >>> sum_of_digit_factorial(0)
      1
      """
      return sum(factorial(int(char)) for char in str(n))
  
  
  def solution() -> int:
      """
      Returns the sum of all numbers whose
      sum of the factorials of all digits
      add up to the number itself.
      >>> solution()
      40730
      """
      limit = 7 * factorial(9) + 1
      return sum(i for i in range(3, limit) if sum_of_digit_factorial(i) == i)
  
  
  if __name__ == "__main__":
      print(f"{solution() = }")
  
new_contents: """
  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.
  """
  
  from math import factorial
  
  DIGIT_FACTORIAL = {str(d): factorial(d) for d in range(10)}
  
  
  def sum_of_digit_factorial(n: int) -> int:
      """
      Returns the sum of the factorial of digits in n
      >>> sum_of_digit_factorial(15)
      121
      >>> sum_of_digit_factorial(0)
      1
      """
      return sum(DIGIT_FACTORIAL[d] for d in str(n))
  
  
  def solution() -> int:
      """
      Returns the sum of all numbers whose
      sum of the factorials of all digits
      add up to the number itself.
      >>> solution()
      40730
      """
      limit = 7 * factorial(9) + 1
      return sum(i for i in range(3, limit) if sum_of_digit_factorial(i) == i)
  
  
  if __name__ == "__main__":
      print(f"{solution() = }")
  
subject: Improve Project Euler problem 034 solution 1 (#5165)