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Convert 32-bit integer to hexadecimal

This question evaluates understanding of integer representation, hexadecimal notation, bitwise operations, and 32-bit two's complement arithmetic. It is commonly asked to assess low-level data representation and edge-case handling within the Coding & Algorithms domain, and it tests practical implementation skills alongside conceptual understanding of binary and base conversion.

Problem

Given a 32-bit signed integer num, return its hexadecimal representation as a string.

Requirements

Use lowercase letters a-f.
Do not include leading zeros (unless the value is exactly zero).
For negative numbers, return the hexadecimal representation of the corresponding 32-bit two's complement value.

Input

Integer num in range [-2^31, 2^31 - 1]

Output

A string containing the hexadecimal representation.

Examples

num = 26 → "1a"
num = 0 → "0"
num = -1 → "ffffffff"

Follow-ups (optional)

Implement without using built-in base conversion utilities (e.g., no toString(16) / format).

Convert 32-bit Integer to Hexadecimal

Constraints

-2^31 <= num <= 2^31 - 1
Output uses lowercase letters a-f.
No leading zeros, except num = 0 which returns "0".
Negative numbers use 32-bit two's complement representation.

Hints

Handle num == 0 as a special case up front, otherwise the loop produces an empty string.
For negative numbers, add 2^32 (1 << 32) to recover the unsigned 32-bit two's complement value, then convert that.
Process 4 bits (one hex nibble) at a time: take num & 0xf to index into "0123456789abcdef", then right-shift by 4.
Build the digits from least-significant to most-significant, then reverse the result before returning.