Write isPalindrome(str) that returns true if the string reads the same forwards and backwards, ignoring case and any non-alphanumeric characters.
Signature: isPalindrome(str) => boolean
Examples: "Racecar" → true, "A man, a plan, a canal: Panama" → true, "hello" → false.
Normalize first: lowercase and strip non-alphanumerics with a regex.
Compare the cleaned string to its reverse (split/reverse/join).
Test natijalarini ko'rish uchun kodingizni ishga tushiring.