Get all digits in a number
Get all digits in a number with minimum space.
Given a positive integer num, the following function iterates its digits from the most insignificant digit to the most significant one:
python def get_digits_right_to_left(num: int): while num > 0: yield num % 10 num //= 10
Here’s another way to write it using Python’s divmod function:
python def get_digits_right_to_left(num: int): while num > 0: num, digit = divmod(num, 10) yield digit
Can we iterate the digits from the most significant digit to the most insignificant one?
python3 def get_digits(num: int): div = 1 while num // div: div *= 10 div //= 10 while div: yield num // div num %= div div //= 10
Another version using divmod:
python3 def get_digits(num: int): div = 1 while num // div: div *= 10 div //= 10 while div: digit, num = divmod(num, div) div //= 10 yield digit
Find the number of digits that evenly divide a positive number
Among all the digits of a positive integer num, write a function to determine how many of them evenly divide num. For example, 13204 has 3 digits that evenly divide 13204: 1, 2, and 4 since 13204 % 1 = 13204 % 2 = 0 = 13204 % 4 = 0.
Note that digit 0 does not divide any positive integer.
python3 def count_digits_evenly_divide(num: int) -> int: return sum(d != 0 and num % d == 0 for d in get_digits(num))
Self-dividing number
A self-dividing number is a number that is divisible by every digit it contains.
For example, 128 is a self-dividing number as 128 % 1 = 128 % 2 = 128 % 8 = 0.
A self-dividing number is not allowed to contain the digit zero.
The function below checks if a number is self-dividing:
python3 def is_self_dividing(num: int) -> bool: return all(d != 0 and num % d == 0 for d in get_digits(num))
Exercises
- Subtract the Product and Sum of Digits of an Integer
- Add Digits
- Maximum Number of Balls in a Box
- Sum of Digits in the Minimum Number
- Self-dividing numbers
- Reverse Integer
- Plus One
- Base 7