Palindrome Number
Recognize the pattern
Brute force idea
If you approach Palindrome Number in the most literal way possible, you get this: Convert to string and compare reversed. It is a fair place to begin because it matches the surface of the question, yet it does not capture the deeper structure that makes the problem simpler.
Better approach
A calmer way to see Palindrome Number is this: Reverse only half the digits and compare. The goal is not to be clever for its own sake, but to remember the one relationship that keeps the solution grounded as you move forward.
Key invariant
The truth you want to protect throughout Palindrome Number is this: Reverse digits until the reversed half is >= the remaining half. If that remains true after every update, the rest of the reasoning has a stable place to stand.
Watch out for
A common way to get lost in Palindrome Number is this: Negative numbers are never palindromes, and numbers ending in 0 (except 0 itself) aren't either. Most mistakes here are not about syntax; they come from losing track of what your state, pointer, or structure is supposed to mean.