Add Digits
Given an integer num, repeatedly add all its digits until the result has only one digit, and return it.
Example 1:
Input: num = 38
Output: 2
Explanation: The process is
38 --> 3 + 8 --> 11
11 --> 1 + 1 --> 2
Since 2 has only one digit, return it.
Example 2:
Input: num = 0
Output: 0
Constraints:
0 <= num <= 231 - 1
Follow up: Could you do it without any loop/recursion in O(1) runtime?
思路一：模拟，直接循环求解
public int addDigits(int num) {
int temp = num;
while (num > 9) {
temp = 0;
while (num > 0) {
temp += num % 10;
num /= 10;
}
num = temp;
}
return temp;
}
思路二：数学，(num - 1) % 9 + 1
标签：return,temp,--,int,258,num,easy,leetcode From： https://www.cnblogs.com/iyiluo/p/16825900.html