【ruby】leetcode 练习 ：Add Digits

Given an integer num, repeatedly add all its digits until the result has only one digit, and return it.

Example 1:

Input: num = 38
Output: 2

Explanation: The process is
38 --> 3 + 8 --> 11
11 --> 1 + 1 --> 2
Since 2 has only one digit, return it.

Example 2:

Input: num = 0
Output: 0

def add_digits(num)  while num > 9      num = num.to_s.chars.sum{ |s| s.to_i }   end  numend

也可以试着练习换换不同写法

def add_digits(num)  while num > 9      num = num.to_s.chars.sum(&:to_i)  end  numend

参考资料：Ruby - &: And &method With To_proc