prg pract 1 2017

public class PRGString {
    // instance variables - replace the example below with your own
    public static boolean esPrefijo(String a, String b) {
        if (a.equals("")) { return true; }
        if (a.length() > b.length() || !a.equals("") && b.equals("")) { return false; }
        else {
            if (a.charAt(0) == b.charAt(0)) {
                return esPrefijo(a.substring(1, a.length()), b.substring(1, b.length()));
            }
            else return false;
        }
    }


    public static boolean esSubcadena(String a, String b) {
        if (a.equals("")) { return true; }
        if (a.length() > b.length() || !a.equals("") && b.equals("")) { return false; }
        else {
            if (a.charAt(0) == b.charAt(0)) {
                if (esPrefijo(a.substring(1, a.length()), b.substring(1, b.length()))) {return true;}
                else return esSubcadena(a, b.substring(1, b.length()));
            }
            else {
                return esSubcadena(a, b.substring(1, b.length()));
            }
        }
    }


    public static boolean esPalindromoSA(String a) {
        if (a.length() <= 1) { return true; }
        if (!Character.isLetter(a.charAt(0))) {
            return esPalindromoSA(a.substring(1, a.length()));
        }
        if (!Character.isLetter(a.charAt(a.length() -1))) {
            return esPalindromoSA(a.substring(0, a.length()-1));
        }
        if (Character.toUpperCase(a.charAt(0)) == Character.toUpperCase(a.charAt(a.length()-1))) {
            return esPalindromoSA(a.substring(1, a.length()-1));
        }
        else return false;
    }


    public static char miToUpperCase(char a) {
        String ac = "ÀÁÈÉÌÍÒÓÙÚÑ";
        String sinac = "AAEEIIOOUUN";
        char letraEnCurso = Character.toUpperCase(a);
        int pos = ac.indexOf(Character.toUpperCase(letraEnCurso));
        if (pos >= 0) { return sinac.charAt(pos); }
        else return letraEnCurso;
    }


        public static boolean esPalindromo(String a) {
        if (a.length() <= 1) { return true; }
        if (!Character.isLetter(a.charAt(0))) {
            return esPalindromo(a.substring(1, a.length()));
        }
        if (!Character.isLetter(a.charAt(a.length() -1))) {
            return esPalindromo(a.substring(0, a.length()-1));
        }
        if (miToUpperCase(a.charAt(0)) == miToUpperCase(a.charAt(a.length()-1))) {
            return esPalindromo(a.substring(1, a.length()-1));
        }
        else return false;
    }
}