[codewars_python]Sum

• 2020 年 1 月 16 日
• 筆記

Instructions

In this kata, you must create a digital root function.

A digital root is the recursive sum of all the digits in a number. Given n, take the sum of the digits of n. If that value has more than one digit, continue reducing in this way until a single-digit number is produced. This is only applicable to the natural numbers.

Here's how it works:

digital_root(16)  => 1 + 6  => 7    digital_root(942)  => 9 + 4 + 2  => 15 ...  => 1 + 5  => 6    digital_root(132189)  => 1 + 3 + 2 + 1 + 8 + 9  => 24 ...  => 2 + 4  => 6    digital_root(493193)  => 4 + 9 + 3 + 1 + 9 + 3  => 29 ...  => 2 + 9  => 11 ...  => 1 + 1  => 2

My solution:

def digital_root(n):      lst = [int(x) for x in str(n)]      result = sum(lst)      if result < 10:          return result      else:          return digital_root(result)

Best solution:

def digital_root(n):      return n if n < 10 else digital_root(sum(map(int,str(n))))