/* A happy number is a number whose sum of digits is calculated until the sum is a single digit,
and this sum turns out to be 1 */
// Copyright 2019 TheAlgorithms contributors
#include <iostream>
int main() {
int n, k, s = 0, d;
std::cout << "Enter a number:";
std::cin >> n;
s = 0;
k = n;
while (k > 9) {
while (k != 0) {
d = k % 10;
s += d;
k /= 10;
}
k = s;
s = 0;
}
if (k == 1)
std::cout << n << " is a happy number" << std::endl;
else
std::cout << n << " is not a happy number" << std::endl;
return 0;
}