import java.util.ArrayList;

public class P11 implements IP11 {
    private void printChar(char toPrint, int times) {
        if (times > 0) {
            System.out.print(toPrint);
            printChar(toPrint, times - 1);
        }
    }

    private void printPattern(int stars, int stripes) {
        if (stripes >= 0) {
            printChar('*', stars);
            printChar('-', stripes);
            System.out.println();
            printPattern(stars + 1, stripes - 1);
        }
    }

    @Override
    public void printPattern(int n) {
        printPattern(0, n);
    }

    private int convertNum(int[] num, int idx, int lastIdx) {
        if (idx == lastIdx) {
            return num[idx];
        } else {
            return (int) (convertNum(num, idx + 1, lastIdx) + num[idx] * Math.pow(10, (lastIdx - idx)));
        }
    }

    @Override
    public int convertNum(int[] num) {
        return convertNum(num, 0, num.length - 1);
    }

    private ArrayList<String> intersection(ArrayList<String> AL1, ArrayList<String> AL2, int remaining) {
        if (remaining == 0) {
            return new ArrayList<String>();
        } else {
            String item = AL1.remove(0);
            ArrayList<String> res = intersection(AL1, AL2, remaining - 1);
            if (AL2.contains(item)) {
                res.add(0, item);
            }
            return res;
        }
    }

    @Override
    public ArrayList<String> intersection(ArrayList<String> AL1, ArrayList<String> AL2) {
        return intersection( new ArrayList<String>(AL1), AL2, AL1.size());
    }

    public static void main(String[] args) {
        P11 inst = new P11();

        inst.printPattern(3);

        int[] num123 = {1, 2, 3};
        System.out.println(inst.convertNum(num123));

        ArrayList<String> AL1 = new ArrayList<String>();
        ArrayList<String> AL2 = new ArrayList<String>();
        AL1.add("a");
        AL1.add("b");
        AL1.add("c");
        AL2.add("b");
        AL2.add("c");
        AL2.add("d");
        AL2.add("e");
        ArrayList<String> intersect = inst.intersection(AL1, AL2);
        System.out.println(AL1 + " intersect " + AL2 + " = " + intersect);
    }
}