Is it a palindrome? (Java)
Java interview exercise on Strings, difficulty 1 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write isPalindrome(s) that returns true when s reads the same forwards and backwards, considering only letters and digits and ignoring case. The empty string is a palindrome. Do it with two indexes walking inwards, not by building a reversed copy.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.