// 258. Add Digits #include // given an integer 'num', repeatedly add all its digits until // the result has onlye one digit and return it int addDigits(int num) { int sum = 0; while (num) { sum += num % 10; num /= 10; } if (sum < 10) return sum; else return addDigits(sum); } int main() { printf("%d\n", addDigits(38)); // expect: 2 printf("%d\n", addDigits(0)); // expect: 0 }