Here is the problem link: Happy Number

Problem Description:

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, and 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 numbers.

Return True if n is a happy number, and False if not.

Example: 

Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Solution:

  1. You should not care about negative numbers. If the input is less than 1 the result is always false.
  2. I just try to find the ending of each number between 1-9. I saw each of the numbers except 1 & 7 create an infinitive loop. Where all of them produce 4 at certain iterations.


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