The inspection rail
01/03Valid Palindrome
Match the edges. Keep the middle honest.
The challenge, in plain language +
A display label may contain letters, digits, spaces, and punctuation. Decide whether its letters and digits read the same from either end when letter case is ignored. Return a boolean. For this exercise, inputs contain ASCII characters, and an empty meaningful sequence counts as a palindrome.
Which wording most directly suggests two inward-moving pointers?
This lesson uses 2D: exact positions, widths and comparisons are easier to read in one plane.