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

One solution is to convert number to string and then handle trailing 0s. Anyway, here is a solution that uses division and multiplication.

class Solution {
    public int reverse(int x) {
        if (x == 0) return 0;
        boolean isNegative = false;
        if (x < 0) {
            x = -x;
            isNegative = true;
        }
        int reversed = 0;
        int prev_reversed = 0;
        while (x > 0) {
            reversed = reversed * 10 + x % 10;
            if (reversed / 10 != prev_reversed) return 0;
            prev_reversed = reversed;
            x /= 10;
        }

        return isNegative ? -reversed : reversed;
    }
}