Determine Whether an Integer Is a Palindrome

Question

The candidate is asked to determine if a given integer is a palindrome, meaning it reads the same forwards and backwards.

Codemia · Accepted Answer

To determine whether an integer is a palindrome, we can convert the integer to a string and check if it reads the same forwards and backwards. However, we can also solve this problem without converting to a string by reversing the integer mathematically.

Here is a Python implementation of the algorithm that checks if an integer is a palindrome:

```python
def is_palindrome(x: int) -> bool:
    # Negative numbers are not palindromes
    if x < 0:
        return False
    # Initialize variables for the reversed number
    original = x
    reversed_num = 0
    while x > 0:
        digit = x % 10
        reversed_num = reversed_num * 10 + digit
        x //= 10
    # Check if the original number and reversed number are the same
    return original == reversed_num
```

The time complexity of this algorithm is O(n), where n is the number of digits in the integer. This is because we process each digit once. The space complexity is O(1) since we are using a constant amount of space for the variables.

When implementing this solution, it is crucial to handle edge cases such as:
1. Negative integers, which cannot be palindromes.
2. Single-digit integers, which are always palindromes.
3. Large integers that may cause overflow in some languages, but Python handles large integers natively.

Interviewers are looking for clarity in the candidate's thought process, the ability to write clean and efficient code, and an understanding of the underlying concepts. They appreciate candidates who can discuss edge cases and complexities, demonstrating a comprehensive grasp of the problem.

Determine Whether an Integer Is a Palindrome

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