Valid Palindrome

Difficulty: Easy · Topic: Arrays & strings

Given a string s, return True if it reads the same forwards and backwards considering only alphanumeric characters and ignoring case.

Examples

is_palindrome("A man, a plan, a canal: Panama")
→ true

Cleaned: 'amanaplanacanalpanama'.

is_palindrome("race a car")
→ false

Target complexity: time O(n), space O(n)

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