The above function takes a C++ string as input and returns true if an input string is a palindrome and false if it is not. You can do this by checking if the first character equals the last character, and so on. You may choose a recursive implementation in this case, although it is not required. If you chose a recursive implementation you may or may not choose to write a helper function. You wont need a helper function is you used the substr (substring) function appropriately in your recursive calls.

/* Precondition: s1 is a valid 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 may provide a recursive OR non-recursive solution*/ bool isPalindrome(const string s1) return true