202. 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.

 

Example 1:

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

Example 2:

Input: n = 2
Output: false

 

Constraints:

• 1 <= n <= 231 - 1

Soluation:

In Javascript:

var isHappy = function(n) {

    let count = 0, result = false;

if(n==1){

    result = true;

  }

while(n!=1){

  let sum = 0;

  let data = n.toString();

  for(let i=0; i<data.length; i++){

  sum += (data[i]*data[i]);

  count++;

  }

  n = sum;

  if(count>25){

    result = false;

    break;

  }

  if(n==1){

    result = true;

  }

}

return result;

};