Is it a palindrome? P50497

Write a function that tells if @s@ is a palindrome or not. Remember that a word is a palindrome if it reads the same from left to right than from right to left. In this exercise, @s@ can be rather large; this is why it is passed by reference.

In order to compare the efficiency of your solution against the efficiency of the solution of the Judge, start checking @s@ from its ends.

Interface

bool is_palindrome(const string& s);

int is_palindrome(const char s[], int ssize);

public static boolean isPalindrome(String s);

is_palindrome(s)  # returns bool

is_palindrome(s: str) -> bool

Observation

You only need to submit the required procedure; your main program will be ignored.