Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. The sign is preserved, so reversing a negative number stays negative.

If reversing x causes the value to go outside the signed 32-bit integer range [-2^31, 2^31 - 1] (that is, [-2147483648, 2147483647]), return 0 instead.

Assume the environment does not allow you to store 64-bit integers — you must detect the overflow rather than rely on a wider type (though the reference solutions below use a wider accumulator where the language makes that the clean choice).

Input / output

• Input: x: int
• Output: int — the reversed value, or 0 on overflow

Constraints

• -2147483648 <= x <= 2147483647

Follow-up

Trailing zeros (as in 120 -> 21) disappear naturally. How would you detect overflow using only 32-bit arithmetic, by comparing against 2147483647 / 10 before each multiply-and-add step?