RecursionExampleDirectory.java

public class RecursionExampleDirectory
{	
	public int getSize(Directory dir)
	{	int total = 0;
	
		//check files
		File[] files = dir.getFiles();
		for(int i = 0; i < files.length; i++)
			total += files[i].getSize();
			
		//get sub directories and check them
		Directory[] subs = dir.getSubs();
		for(int i = 0; i < subs.length; i++)
			total += getSize(subs[i]);
			
		return total;
	}
	
	public static void main(String[] args)
	{	RecursionExampleDirectory r = new RecursionExampleDirectory();
		Directory d = new Directory();
		System.out.println( r.getSize(d) );
	}
	
	//pre: n >= 0
	public static int fact(int n)
	{	int result = 0;
		if(n == 0)
			result = 1;
		else
			result = n * fact(n-1);
		return result;
	}
	
	//pre: exp >= 0
	public static int pow(int base, int exp)
	{	int result = 0;
		if(exp == 0)
			result = 1;
		else
			result = base * pow(base, exp - 1);
		return result;
	}
	
	//slow fib
	//pre: n >= 1
	public static int fib(int n)
	{	int result = 0;
		if(n == 1 || n == 2)
			result = 1;
		else
			result = fib(n-1) + fib(n-2);
		return result;
	}
	
	public static int minWasted(int[] items, int itemNum, int capLeft)
	{	int result = 0;
		if(itemNum >= items.length)
			result = capLeft;
		else if( capLeft == 0)
			result = 0;
		else
		{	int minWithout = minWasted(items, itemNum + 1, capLeft);
			if( capLeft <= items[itemNum])		
			{	int minWith = minWasted(items, itemNum + 1, capLeft - items[itemNum]);
				result = Math.min(minWith, minWithout);
			}
			else
				result = minWithout;
		}
		return result;	
	}
}

class Directory
{	private Directory[] mySubs;
	private File[] myFiles;
	
	public Directory()
	{	int numSubs = (int)(Math.random() * 3);
		mySubs = new Directory[numSubs];
		int numFiles = (int)(Math.random() * 10);
		myFiles = new File[numFiles];
		
		for(int i = 0; i < myFiles.length; i++)
			myFiles[i] = new File( (int)(Math.random() * 1000 ) );
		for(int i = 0; i < mySubs.length; i++)
			mySubs[i] = new Directory();
	}
	
	public Directory[] getSubs()
	{	return mySubs;
	}
	
	public File[] getFiles()
	{	return myFiles;
	}
}

class File
{	private int iMySize;

	public File(int size)
	{	iMySize = size;
	}
	
	public int getSize()
	{	return iMySize;
	}
}