Download Lecture 8

Lecture 8
Trees
sortTree Class
public class sortTree
{
public Node root = null;
public sortTree(double val)
{
root = new Node(val);
}
public Node add(Node node, double val)
{
if (node == null)
return node = new Node(val);
if (val < node.data)
node.left = add(node.left, val);
else
node.right = add(node.right, val);
return node;
}
protected class Node
{
public void showAll(Node node)
double data;
{
Node left;
if (node != null)
Node right;
{
showAll(node.left);
public Node(double val)
System.out.println(node.data);
{
showAll(node.right);
this(val,null,null);
}
}
}
public Node(double val, Node left_node, Node right_node)
{
data = val;
left = left_node;
right = right_node;
}
}
protected class Node
{
double data;
Node left;
Node right;
public Node(double val)
{
this(val,null,null);
}
public Node(double val, Node left_node, Node right_node)
{
data = val;
left = left_node;
right = right_node;
}
}
data
left
null
right
null
TreeSort add( ) Method
5, 3, 7, 2, 1, 8, 9, 0, 4, 6
5
3
2
7
4
6
1
0
8
9
public Node add(Node node, double val)
{
if (node == null)
return node = new Node(val);
if (val < node.data)
node.left = add(node.left, val);
else
node.right = add(node.right, val);
return node;
}
sortTreeDemo
public class sortTreeDemo
{
public static void main(String[] args)
{
sortTree myTree = new sortTree(Math.random()*1000.0);
for(int i=1;i<1000000;i++)
myTree.add(myTree.root,Math.random()*1000.0);
myTree.showAll(myTree.root);
}
}
TreeSort for Strings
public class TreeSort
{
public static void main(String []args)
{
String[] words = {"this", "is", "a", "test", "this", "is", "only", "a", "test"};
Tree tree= new Tree();
for(int i=0;i<words.length;i++)
tree.insert(words[i]);
tree.showNodes();
}
}
The Tree Class
class Tree
{
Node root=null;
public void showNodes()
{
if (root==null)
return;
else
root.showNodes();
}
public void insert(Comparable c)
{
if (root==null)
root = new Node(c);
else
root.insert(c);
}
}
The Node Class for TreeSort
class Node
{
int count;
Node left;
Node right;
Comparable key;
public void insert(Comparable c)
{
if(c.compareTo(this.key)<0)
{
if (left == null)
left=new Node(c);
else
left.insert(c);
}
public Node(Comparable c)
{
key=c;
count=1;
left=null;
right=null;
}
public void showNodes()
{
if (left!=null)
left.showNodes();
System.out.println(key + "
if (right!=null)
right.showNodes();
}
if(c.compareTo(this.key)==0)
this.count += 1;
" + this.count);
if(c.compareTo(this.key)>0)
{
if (right == null)
right=new Node(c);
else
right.insert(c);
}
}
}
Redirecting Standard Output to a File
an important side issue
import java.io.*;
public class outputRedirectDemo
{
public static void main(String[] args) throws FileNotFoundException
{
File file = new File("redirect.txt");
PrintStream printStream = new PrintStream(new FileOutputStream(file));
System.out.println("1");
System.setOut(printStream);
System.out.println("2");
}
}
Using TreeSort in the Lexicon Demo Program
import java.util.Scanner;
import java.io.*;
public class LexiconDemo2
{
public static String[] words = new String[1000000];
public static int[] counts = new int[1000000];
public static int numwords = 0;
public static void main(String[] args) throws FileNotFoundException
{
FileReader reader = new FileReader("warandpeace.txt");
Scanner in = new Scanner (reader);
File file = new File("warandpeace.out");
PrintStream printStream = new PrintStream(new FileOutputStream(file));
System.setOut(printStream);
Tree tree= new Tree();
while(in.hasNextLine())
{
String line = in.nextLine();
String[] str = line.split("[.,:;?(){}!-= ]");
for(int i = 0;i<str.length;i++)
if(str[i].length()>0)
tree.insert(str[i].toLowerCase());
}
tree.showNodes();
}
}
Run-Time Analysis
What are the run-times (order of complexity) for LexiconDemo and
LexiconDemo2?
O(n2)
O(n lg2n)
Estimate the time to execute for n= 500,000 in seconds on our lab
computers.