check for positive happy number in ruby

happy_number.rb

# a tail call optimized ruby script to find happy number

def happy_number?(num, seen_number = {})
  # store num in hash for quick lookup
  seen_number[num] = num

  total = num
          .to_s
          .chars
          .reduce(0) { |acc, digit| acc + digit.to_i ** 2 }
  
  return true if total == 1
  return false if seen_number[total]
  happy_number?(total, seen_number)
end

# test cases
puts happy_number?(6) == false
puts happy_number?(7) == true

This can be:
total = num .to_s .chars .reduce(0) { |acc, digit| acc + digit.to_i ** 2 }

total = num.digits.reduce(0) { |acc, digit| acc + digit ** 2 }

This way we don't need to covert to_s and then to_i again.

.digits is not very performant :) @veekram

https://stackoverflow.com/questions/47953598/rubys-digits-method-performance