public class Reverse {
  private static final int max = Integer.MAX_VALUE;
  private static final int min = Integer.MIN_VALUE;

  public int reverse(int x) {
    // setup -> reduce the problem to 'positive int' (maybe unnecessary)
    boolean isNegative = (x < 0);
    int upperBound = Math.abs(isNegative ? min / 10 : max / 10);
    int check = Math.abs(isNegative ? min % 10 : max / 10);

    x = Math.abs(x);
    int ret = 0;

    while (x != 0) {
      int digit = x % 10;
      x /= 10;
      if ((ret > upperBound) || (ret == upperBound) && (digit == check)) {
        return 0;
      }
      ret = 10 * ret + digit;
    }
    return isNegative ? -1 * ret : ret;
  }
}