Leetcode题解 258. Add Digits

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.

For example:

Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.

public static int addDigits(int num) {        if (num / 10 == 0) {            return num;        }        int result = num;        Stack<Integer> mStack = new Stack<Integer>();        while (result / 10 != 0) {            while (result != 0) {                mStack.push(result % 10);                result /= 10;            }            while (mStack.size() > 0) {                result += mStack.pop();            }        }        return result;    }