leetcode之258. Add Digits（C++解法）

題目：
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.
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class Solution {
public:
int addDigits(int num) {
int temp;
for(;;)
{
temp=num;
num=0;
for(;temp>0;temp=temp/10)
num=num+temp%10;
if(num<10)
break;
}
return num;
}
};