Happy Number

In reviewing the problem directions before I attempt it, I am honestly a bit confused as to why it says there is a two pointer approach. Given my interpretation, I think that the easiest implementation would be a recursive solution with just math and a table. I am once again reminded of 9. Palindrome Number. My plan is to take each digit and square it using modulo and div, and then recursively calling isHappy() we reach 1. This helper function gets the digits from n.

func getSum(n int) int {
	a := 0
	for n > 0 {
		digit := n % 10 
		n /= 10
		a += digit*digit
	}

    return a
}

And each time before getting the new digits, the current n is added to a hashmap. This way, if a number is seen a second time, its evidence that there is an infinite loop afoot. Hence the following section.

if seenNumbers[n] {
			return false
		}
        seenNumbers[n] = true

func isHappy(n int) bool {
	seenNumbers := make(map[int]bool)

	for {
		if n == 1 {
			return true
		}
		if seenNumbers[n] {
			return false
		}
        seenNumbers[n] = true
		n = getSum(n)
	}
}

func getSum(n int) int {
	a := 0
	for n > 0 {
		digit := n % 10 
		n /= 10
		a += digit*digit
	}

    return a
}