// CSE 143, Winter 2010, Marty Stepp
// This program uses recursion to decide whether strings are palindromes.

public class Palindromes {
    public static void main(String[] args) {
        System.out.println(isPalindrome("madam"));
        System.out.println(isPalindrome("racecar"));
        System.out.println(isPalindrome("step on no pets"));
        System.out.println(isPalindrome("able was I ere I saw elba"));
        System.out.println(isPalindrome("Java"));
        System.out.println(isPalindrome("rotater"));
        System.out.println(isPalindrome("byebye"));
        System.out.println(isPalindrome("notion"));
    }
    
    // Returns true if the given string reads the same forwards as backwards.
    public static boolean isPalindrome(String s) {
        if (s.length() <= 1) {
            // base case: one letter or empty string
            return true;
        } else {
            // recursive case: 2 or more letters
            char first = s.charAt(0);
            char last = s.charAt(s.length() - 1);
            String middle = s.substring(1, s.length() - 1);
            return first == last && isPalindrome(middle);
        }
    }
}