Palindrome Checker

StringTwo Pointers

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Example 1

Input

[
  "A man, a plan, a canal: Panama"
]

Output

true

Explanation. Ignoring punctuation and case, 'amanaplanacanalpanama' is a palindrome.

Example 2

Input

[
  "race a car"
]

Output

false

Explanation. Ignoring punctuation and case, 'raceacar' is not a palindrome.

Example 3

Input

[
  " "
]

Output

true

Explanation. An empty string or a string with just space characters is considered a palindrome.

Example 4

Input

[
  "Noon"
]

Output

true

Explanation. Ignoring case, 'noon' is a palindrome.

Follow-up: Can you solve the problem without using extra space?

Constraints:

The input string will contain only printable ASCII characters.