Write an algorithm to determine if a number 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.
Example:
Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
- Solved in 40 mins without reference
- Used array as storage to refer to previously stored value but could use hash map concept.
/**
* @param {number} n
* @return {boolean}
*/
var isHappy = function(n) {
if (n == 1) return true
let res = n
let stack = []
while (res !== 1 && !stack.includes(res)) {
stack.push(res)
let num = `${res}`
let nums = num.split("")
let sum = 0
nums.forEach(el => {
sum += Math.pow(el, 2)
})
res = sum
if (res === 1) return true
}
return false
}