import java.util.Scanner;

public class RecurPalindrome {

    public static void main(String[] args) {

	// Welcome message 
	System.out.println("\nWelcome to the Palindrome Test Program!");

	// Takes in one user input
	Scanner userInput = new Scanner(System.in);
	System.out.println("\nType in a word and press enter:");
	String word = userInput.nextLine();
	userInput.close();

	// Calling the recursive function here!
	boolean isPalindrome = rPalindrome2(word);

	// Printing out the result
	if (isPalindrome)
	    System.out.println("Palindrome!");
	else
	    System.out.println("Not a palindrome!");
    }

    //
    // rcursive soluton to determining if a string
    // is a palindrome.
    //
    // Note, the explixit base case.
    //
    private static boolean rPalindrome(String s) {

	// Base Case
	if (s.length() <= 1)
	    return true;

	// Recursive Case
	//
	// Check and make appropriate recursive calls
	// Remove any spaces recursively, assuming no special characters
	//
	int length = s.length();
	
	if (s.charAt(0) == ' ')
	    return rPalindrome(s.substring(1,length));
	else if (s.charAt(length-1) == ' ')
	    return rPalindrome(s.substring(0,length-1));
	else if (s.charAt(0) == s.charAt(length-1))
	    return rPalindrome(s.substring(1,length-1));
	else
	    return false;

    }

    //
    // an alternative version
    //
    // Note, the explixit base case.
    //
    private static boolean rPalindrome2(String s) {
	boolean isPal = true;

        if (s.length() > 1) {

        	int length = s.length();

        	if (s.charAt(0) == ' ')
            		isPal = rPalindrome2(s.substring(1,length));
        	else if (s.charAt(length-1) == ' ')
            		isPal = rPalindrome2(s.substring(0,length-1));
        	else if (s.charAt(0) == s.charAt(length-1))
            		isPal = rPalindrome2(s.substring(1,length-1));
        	else
            		isPal = false;
	}

	return( isPal );
    }


}