Valid Palindrome

EasyStringsTwo Pointers

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Given a string s, return true if it is a palindrome, or false otherwise.

Examples

Input: s = "A man, a plan, a canal: Panama"
Output: true
"amanaplanacanalpanama" is a palindrome.
Input: s = "race a car"
Output: false
Input: s = " "
Output: true

Constraints

  • 1 <= s.length <= 2 * 10^5
  • s consists only of printable ASCII characters.

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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