159. Happy Number

Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: - Starting with any positive integer, replace the number by the sum of the squares of its digits. - Repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. - Those numbers for which this process ends in 1 are happy. Return true if n is a happy number, and false if not.