package LabExam;
import java.util.*;

public class Recursion {
    /**
     * Given a string, compute recursively (no loops) a new string
     * where all the lowercase 'x' chars have been changed to 'xyx' chars.
     * <p>
     * changeXY("xyz123") → "xyxyz123"
     * changeXY("xxx") → "xyxxyxxyx"
     * changeXY("()") → "()"
     */
    public String changeXxyx(String str) {

        // TODO: Write a recursive function to complete this method
        //
        // Note: The code below is simply a placeholder to allow the
        // code to compile and run.

       String b;

        char a, d, c;
        a = 'x';
        d = 'y';
        c = 'x';

        StringBuilder sb = new StringBuilder();
        sb.append(a);
        sb.append(d);
        sb.append(c);
        b = sb.toString();

        if (str.equals(""))
            return "";
       char r = str.charAt(0);
        return (r == 'x' ? b :r) + changeXxyx(str.substring(1));
    }

    }