---
title: "ByteByteGo: Reverse 32-Bit Integer"
url: https://perrotta.dev/2025/11/bytebytego-reverse-32-bit-integer/
last_updated: 2026-01-03
---


[ByteByteGo: Reverse 32-Bit Integer](https://bytebytego.com/exercises/coding-patterns/math-and-geometry/reverse-32-bit-integer):

## Strings

```python
def reverse_32_bit_integer(n: int) -> int:
    ans = ""

    s = str(n)[::-1]

    # 420
    # 024

    # -15
    # 51-

    is_negative = n < 0
    is_beginning = True

    for i, c in enumerate(s):
        if i == (len(s) - 1) and is_negative:
            continue

        if c == '0' and is_beginning:
            continue

        ans += c

        is_beginning = False

    ans = int(ans) * (-1 if is_negative else 1)

    return ans if (-1 * 2**31 <= ans <= 2**31 - 1) else 0
```

## Numbers

```python
def reverse_32_bit_integer(n: int) -> int:
    ans = 0
    is_negative = -1 if n < 0 else 1
    n = abs(n)

    while n != 0:
        digit = n % 10
        n //= 10

        # Check for overflow: positive
        if ans > (2**31 - 1) // 10:
            return 0

        ans = ans * 10 + digit

    return is_negative * ans
```