Leetcode Note: Go - Happy Number

func isHappy(n int) bool {    
    record := map[int]bool{n: true}
    
    for n != 1 {
        var sum int
        for n != 0 {
            num := n%10
            sum += num * num
            n /= 10
        }
        n = sum
        if record[n] {
            return false
        }
        record[n] = true
    }
    
    return true
}