The task involves inverting the digits of a standard 32-bit signed integer. For example, an input of 123 produces 321, while -789 yields -987. A critical requirement dictates that the function must return 0 if the reversed value exceeds the representabel range of a 32-bit signed integer (-2,147,483,648 to 2,147,483,647).

String-Based Inversion

Python’s string handling capabilities allow for a concise implementation. By isolating the sign, converting the absolute value to a string, and applying slice notation for reversal, the digits can be efficiently inverted. After reconstruction, the original sign is reapplied, and the result is validated against the numerical boundaries.

class DigitInverter:
    def flip(self, source: int) -> int:
        MAX_LIMIT = 2147483647
        MIN_LIMIT = -2147483648
        
        polarity = -1 if source < 0 else 1
        inverted = int(str(abs(source))[::-1])
        final_val = polarity * inverted
        
        if final_val < MIN_LIMIT or final_val > MAX_LIMIT:
            return 0
            
        return final_val

Arithmetic Digit Extraction

A purely mathematical approach avoids string conversion overhead and aligns with traditional low-level integer processing. This technique iteratively isolates the least significant digit using the modulo operator and shifts the accumulated result left by multiplying by ten. Python’s arbitrary-precision integers safely handle intermediate calculations, allowing a straightforward boundary check after reconstruction.

class MathReverser:
    def flip(self, input_num: int) -> int:
        UPPER = 2**31 - 1
        LOWER = -2**31
        
        direction = -1 if input_num < 0 else 1
        positive_magnitude = abs(input_num)
        reversed_total = 0
        
        while positive_magnitude > 0:
            reversed_total = (reversed_total * 10) + (positive_magnitude % 10)
            positive_magnitude //= 10
            
        output = direction * reversed_total
        
        if output < LOWER or output > UPPER:
            return 0
            
        return output

The arithmetic method processes digits through repeated division and modulo operations, reconstructing the number in reverse order. Both implementations correctly manage sign preservation and enforce the 32-bit overflow constraint, with the mathematical variant offering better cross-language portability and predictable memory usage.