Create java recursion

java recursion

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+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;
+	}
+}