7. Reverse Integer

Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123
Output: 321
Example 2:
Input: -123
Output: -321
Example 3:
Input: 120
Output: 21






class Solution {
    public int reverse(int x) {
        long res = 0;
        while(x != 0){
            res = res * 10 + x % 10;
            x = x / 10;
            if(res > Integer.MAX_VALUE || res < Integer.MIN_VALUE){
                return 0;
            }
        }
        return (int)res;
    }
}