import { NotImplementedError } from "../extensions/index.js";

/**
 * Given a number, replace this number with
 * the sum of its digits until we get to a one digit number.
 *
 * @param {Number} n
 * @return {Number}
 *
 * @example
 * For 100, the result should be 1 (1 + 0 + 0 = 1)
 * For 91, the result should be 1 (9 + 1 = 10, 1 + 0 = 1)
 *
 */
export default function getSumOfDigits(n) {
  n = n.toString();
  let res = 0;
  for (let i = 0; i < n.length; i++) {
    res += +n[i];
  }
  if (res > 9) {
    return getSumOfDigits(res);
  }
  return res;
}
