import objectdraw.*;
import java.awt.*;

// Examples of nongraphical recursive methods involving ints and strings.
public class TextRecursion extends FrameWindowController {

    // test the methods
    public void begin() {

        int num = 6;

        int numFactorial = factorial(num);
        System.out.println(num + "! = " + numFactorial);

        int fibNum = fib(num);
        System.out.println("Fibonacci number " + num + " = " + fibNum);

        String text = "I like recursion";

        int textLength = length(text);
        System.out.println("The length of \"" + text + "\" is " + textLength);

    }

    // recursive implementation of factorial
    public int factorial(int n) {
        if (n == 0) {
            return 1;
        }
        return n * factorial(n - 1);
    }

    // iterative implementation of factorial
    public int factorialIterative(int n) {
        int result = 1;
        int i = 2;
        while (i <= n) {
            result = result * i;
            i++;
        }
        return result;
    }

    // recursive implementation of fibonacci numbers
    public int fib(int n) {
        if (n == 0 || n == 1) {
            return 1;
        }
        return fib(n - 1) + fib(n - 2);
    }

    // recursive implementation of string length
    public int length(String str) {
        if (str.equals("")) {
            return 0;
        }
        return 1 + length(str.substring(1));
    }

}