How should I practice Valid Palindrome?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Meta onsite interview problems in FastPrep.

Is Valid Palindrome associated with Meta?

FastPrep tags this as a Meta onsite interview coding practice problem when the problem catalog has that company and stage context.

Valid Palindrome

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Problem statement

Given a string s, ignore every character other than ASCII letters and digits, and compare letters without regard to case.

Return true if the remaining characters read identically from left to right and right to left. Otherwise, return false. A string with no remaining characters is a palindrome.

Function

isPalindrome(s: String) → boolean

Examples

Example 1

s = "A man, a plan, a canal: Panama"return = true

Ignoring spaces, punctuation and case leaves amanaplanacanalpanama, which reads the same in both directions.

Example 2

s = "race a car"return = false

The retained string is raceacar; its fourth character from the left is e, while its fourth character from the right is a.

Example 3

s = " "return = true

Removing the space leaves no characters, so the result is true.

Example 4

s = "0P"return = false

Digits are retained. After lowercasing, 0p is not a palindrome.

Constraints

1 <= s.length <= 2 * 10^5.
s contains only printable ASCII characters.