package Inlab9;

public class Recursion
{
    /**
     * Converts a decimal number to a binary one using recursion.
     * Assume the decimal number is >= 1.
     * 
     * @param       number      the decimal number to convert
     * @return      a String representation of the binary number
     */
    public static String convertToBinary(int number)
    {
        if(number < 2)
        {
            return String.format("%d", number);
        }
        else
        {
            return convertToBinary(number / 2) + convertToBinary(number % 2);
        }
    }
    
    /**
     * Find the largest item in an array of integers.  
     * Assume the array contains at least one item.
     * 
     * @param       numbers     an array of integers
     * @return      the largest number in the array of intgers
     */
    public static int largestArrayItem(int [] numbers)
    {
        return largestArrayItemAuxiliary(numbers, 0);
    }
    
    /**
     * The helper method for largestArrayItem.
     * 
     * @param       numbers     an array of integers
     * @param       index       the current index in the array to examine
     * @return      the largest number in the array of integers
     */
    private static int largestArrayItemAuxiliary(int [] numbers, int index)
    {
        if(index == (numbers.length - 1))
        {
            return numbers[index];
        }
        else
        {
            int rest = largestArrayItemAuxiliary(numbers, index+1);
            if(numbers[index] > rest)
            {
                return numbers[index];
            }
            else
            {
                return rest;
            }
        }
    }
}