bool isPalindromeHelper(const char *s1, int len);

/* Precondition: s1 is a valid C-string that may contain upper or lower case alphabets, no spaces or special characters

* Postcondition: Returns true if s1 is a palindrome, false otherwise

*You MUST provide a recursive implementation and are recommended to write a helper function where the recursion actually takes place*/

bool isPalindrome(const char *s1){

return true;

}