Leetcode 9: Palindrome Number - Explained with visualization in Swift

Explanation:

This Swift code checks if an integer is a palindrome. Here's how it works:

1. Handle Negative Numbers:
If the input integer `x` is negative, it cannot be a palindrome. Negative numbers always have a leading minus sign, which will not be the same when reversed. Therefore, the function immediately returns `false`.

2. Reverse the Integer:
`n`: A copy of the original integer `x` is created to avoid modifying the input.
`r`: A variable to store the reversed integer, initialized to 0.
The `while` loop iterates as long as `n` is greater than 0:
`m = n % 10`: Extracts the last digit of `n` using the modulo operator (%).
`r = r * 10 + m`: Appends the extracted digit to the `r` variable.
`n = n / 10`: Removes the last digit from `n` using integer division.

3. Compare Original and Reversed Numbers:
After the loop, `r` will hold the reversed integer.
The function returns `true` if the original number `x` is equal to the reversed number `r`, indicating that it's a palindrome. Otherwise, it returns `false`.

Key Points:

This approach efficiently reverses the integer using basic arithmetic operations.
It avoids string conversions, which can be less efficient.
The code is concise and easy to understand.

Example:

If `x = 121`:
`r` becomes 1, then 12, and finally 121.
Since `x == r`, the function returns `true`.

If `x = -121`:
The function immediately returns `false` because the number is negative.

This code provides a clean and effective solution for checking if an integer is a palindrome in Swift.


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