[LeetCode] Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

每次取出个位，然后放到新的数里。

class Solution {
public:
    int reverse(int x) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int sign = x > 0 ? 1 : -1;
        x = abs(x);
        
        int ret = 0;
        while(x)
        {
            int digit = x % 10;
            ret = ret * 10 + digit;
            x /= 10;
        }
        
        return ret * sign;
    }
};