String Palindrome Verification

Given a string, your task is to determine if it is a palindrome considering only alphanumeric characters.

Input:

The input is a single string without any leading or trailing spaces. All characters are in lowercase.

Output:

The output should be a single line printing 'true' if the string is a palindrome, otherwise 'false'.

Example:

Input: "malayalam" Output: true Explanation: The string "malayalam" reads the same forward and backward, hence it is a palindrome.

Constraints:

0

Question

String Palindrome Verification

Given a string, your task is to determine if it is a palindrome considering only alphanumeric characters.

Input:

The input is a single string without any leading or trailing spaces. All characters are in lowercase.

Output:

The output should be a single line printing 'true' if the string is a palindrome, otherwise 'false'.

Example:

Input: "malayalam"
Output: true
Explanation: The string "malayalam" reads the same forward and backward, hence it is a palindrome.

Constraints:

0 <= N <= 10^6
N is the length of the input string.
Time Limit: 1 second

Note:

Your implementation should return a boolean value. Printing is handled internally.

Accepted Answer

Check if a given string is a palindrome considering only alphanumeric characters.

Remove non-alphanumeric characters from the input string.
Convert the string to lowercase for case-insensitive comparison.
Compare characters from start and end of the string to check for palindrome.
Return 'true' if the string is a palindrome, 'false' otherwise.

Accepted Answer

Method type should be of Boolean type to return the output in true or false.

I will use 2 pointer approach in which i starts from 0th index of string and j starts from s.length()-1 both move till half of string. i increament by 1 and j decrement by 1 if the  both characters have same ASCII value as string deals with characters ASCII value and return true if both characters will same till movement to half of string. Otherwise method will return false if characters will not same in any iteration.

Asked in Amazon