Binary Expression Tree
Apr 23, 2015
So everything in my program is working EXCEPT when it comes to calculating the result. I am supposed to evaluate the expression using postorder traversal to return the answer. I am honestly not sure how I would get the postorder traversal to return the answer to the expression since the only thing we really went over was how it re-ordered the expression so that it would end in the postorder/postfix order. Anyways, currently the way that I have the public int evaluate(Node node)method set up is giving me a result of 0, which obviously is not correct.
Here's the section that I'm having issues with:
public int evaluate(Node node){
if(node.isLeaf()){
return Integer.parseInt(node.value);
}
int result = 0;
int left = evaluate(node.left);
int right = evaluate(node.right);
[code]....
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Dec 2, 2014
Write a Java program to create a binary expression tree in which: leaves are (double) numbers, and interior nodes are binary algebraic operators). As an example, the expression 1 2 + 3 * could be represented as:
The input to the program is an arithmetical expression (already) in postfix notation. Use for testing the sample :
4 8 2 / * 10 7 ‐ + ( equivalent to 4*8/2+(10‐7) ) .
After creating the corresponding expression tree, print it’s traversal in Pre‐Order, In‐Order, and Post‐Order.Evaluate the expression and print its final value (for this example, result should be: 19.00).
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May 6, 2014
I Write a Java program to parse a syntactically correct arithmetical expression and produce an equivalent Expression TREE. Remember, in an expression tree the terminal nodes are variables and constants, and the interior nodes are operators (such as +,-,*,/).
For instance the expression: (1 + 2) * 3 can be represented by the following tree:
INPUT Expression
(1 +2)*3
POSTORDER Expression
1 2 + 3 *
TREE [root=asd.reg.Node@56ddc58]
But when i Execute the program it Shows only Prefix and postfix .But the requered output is in inorder preorder and postorder so how to solve these error
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
import javax.swing.tree.TreeNode;
public class InToPost {
private static String str;
[Code] .....
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Aug 3, 2014
I am trying to build an expression tree program . I try to print it then I have java.nullpointer exception . Is it error in my code or what ?
I have 2 classes
one is BSTreeNode which is the nodes for the tree . It has
public class ExpressionTree {
public BSTreeNode root;
public BSTreeNode curr = root;
ExpressionTree() {
root = new BSTreeNode(null, null, null, null);
curr = root;
[Code] ....
My BSTreeNode
public class BSTreeNode {
BSTreeNode parent;
Object element; // Binary search tree element
BSTreeNode left; // Reference to the left child
BSTreeNode right; // Reference to the right child
// Constructor
BSTreeNode (Object elem)
[Code] ....
The error i am getting is
Exception in thread "main" java.lang.NullPointerException
at binaryexpressiontree.ExpressionTree.insert(ExpressionTree.java:38)
at binaryexpressiontree.test.main(test.java:22)
Java Result: 1
After implementing exception handler what i am getting is
java.lang.NullPointerException
root 1 *
root 2 1 error error error//these error print because of my catch clause
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Apr 2, 2014
I have a list of people with a matching telephone extension number, the people are organised in a hierachy tree with some colleagues at the same level and then some junior colleagues. I have been trying to write code that can find the tree height of any given member but I am unable too. Here is my code so far but the left and right are not working because I have not declared them any where in my code.
Java Code:
//hierarchy rank section 7
// **Depth** from node to root (bottom up)
public int rank(Member p1){
//to do
[code]....
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Mar 24, 2014
So here is the code that I have. The problem is my insert method. It compiles, but it doesn't do so well in the test class I have set up for it.
package SystemandDesign.BinaryTree;
mport java.io.FileInputStream;
import java.io.IOException;
import java.util.List;
import java.io.ObjectInputStream;
import java.util.Scanner;
[code]....
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Nov 26, 2014
I know that for a binary search tree the insert() method is easy. You just kept comparing the values of the nodes, and you would know whether to go left or right depending on the value of the node.However, I am stumped when trying to figure out how to add a node into a normal binary tree where you just keep adding the nodes to the leftmost side, regardless of value.Here is my attempt at the insert() method:
public class RegularTree extends BinaryTree {
public CompleteTree() {
super();
}
public void insert(Comparable item) {
if(this.isEmpty()) {
this.setRoot(new TreeNode(item));
return;
[code]....
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Aug 7, 2014
Is there a way that I can view my entire binary tree on Eclipse? I remember the old IDE that I used, jGrasp, had a feature in its debugging that would allow me to see exactly what was going on and I want to know if Eclipse has the same thing.
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Dec 4, 2014
I have a little problem in my code. Using a threaded binary tree and inorder traversal check if every next element is equal to the previous element + 1. You are allowed to use additional functions as long as they are not recursive. I have implemented everything. Problem is that i cant compare elements as i should. They are type E.
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
import java.util.NoSuchElementException;
import java.util.ArrayList;
[code]....
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Apr 5, 2014
I have written a code to get all the nodes below a current Node and it is working but I need to get it to look better if possible. To get the number of nodes below I have created an Array List, which I then go to the first Node below and add all the people to the Array list on the same level till I get to the end of the level, then I go down again until I cannot go down any more. Is there a way I can have my code without having to use an array List? I have put my code below. The brieff about the tree is that you have a parent and below the Parent are children who can have brothers and sisters next to them and after that they also have children below that. The method is trying to find the number of children below any given child
private LinkedList<Node> TempQueue = new LinkedList<Node>();
public int noOfYoungerChildren(Member p1){
Node tmp = find(p1);
return countYoungerChildren(tmp);
[code]....
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Jan 31, 2014
I create a binary tree and now I would like to display the result in my jsp with conditions.
Each node has 4 elements (id, question, answer, and leftnode rightnode)
If the user clicks "Yes", the program goes to the left of the tree and if he answers "no" to the right of the tree.
For example, the initial question is "you're a man?" If he answers "yes" we will go to the left and page view "you're a singer?" If he answers "no" page displays "you're French? ".
In java, it would
cursor [i]. GetQuestion ()
to the original question.
Then
cursor [i] getQuestion. GetLeftnode ()
For yes and
cursor [i]. GetRightnode (). GetQuestion
for no.
Until the, everything works normally, but when I want to loop until there is no longer any issue by
<c:when test="${not empty cursor[i].getQuestion() }">
The program stops at the first loop and stops it that cursor is not empty
Here is my complete code jstl
<c:set var="cursor" value="${nodes}" scope="session"></c:set>
<c:set var="i" value="0" scope="session"></c:set>
<form>
<c:choose>
<c:when test="${not empty cursor[i].getQuestion() }">
<c:out value="i vaut ${i } au debut de la boucle"></c:out>
[Code] ....
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Mar 24, 2014
So, managed to get my Binary Search Tree to work properly:
package SystemandDesign.BinaryTree;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;
import java.io.ObjectInputStream;
import java.util.Scanner;
[Code] ....
No matter how many times I keep rewritting the testInsert method I get a chock full of errors.
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May 17, 2015
I am trying to implement a simple binary search tree . How can I make a node in the tree which should store two pieces of information: a String variable called name, and a int variable called mark. ..
public class BinarySearchTree<E> implements Comparable<E> {
public BinaryTree<E> root;
int size;
int mark;
String name;
// Constructor
public BinarySearchTree()
[Code]...
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Aug 17, 2014
I don't see any nodes that I add. Not sure why getting this error.
duplicate found
Exception in thread "main" java.lang.NullPointerException
at binarysearchtree.delete(binarysearchtree.java:111)
at binarysearchtree.main(binarysearchtree.java:196)
Java Result: 1
public class node<T>
[Code] .....
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Mar 29, 2015
I have some work where I have to create a binary tree. Anyway I am stuck on one of the classes which has several methods I must fill in! The code is below
The headers for each method are: public Node find (member p1)The method find(Member p1) is used to return the node which contains a particular member. It is a private method because the interface to CabinetTree should not provide direct access to the internal nodes. It makes use of the method Node findNode (Member p1, Node current)
and the next method is : Node findNode(Member p1, Node current) which searches the tree from current node to find a node whose value is equal to the Member p1, i.e. a node in the tree such that p1.equals(current.getMember()) is true. If there is no such node then the method should return null.
public class CabinetTree {
private Node head;
CabinetTree(Member p1) {
head = new Node(p1, null);
[Code] ....
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Apr 23, 2015
The assignment is meant to understand and practice tree concepts, tree traversals and recursion. I am requested to use the tree to print the expressions by three ways and evaluate the expression in post-order. This is my node class,
package hw10;
public class Node {
String value;
Node left, right;
public Node(String value) {
[Code] .....
When i test my code, some trouble like this:
Enter a prefix expression: - + 10 * 2 8 3
prefix expression:
- + 10 * 2 8 3
postfix expression:
+ 10 * 2 8 3 -
infix expression:
( ( 10 + ( 2 * 8 ) ) - 3 )
[Code] .....
the error lines:
75: double left = evaluate(node.left);
107: evaluate(root);
In the Instruction, which said:
- int evaluate(Node node)
Given the root node of an expression tree, evaluates the expression using post-order traversal and returns the answer. main method Testing logic.
And I found the postfix expression was wrong, it should be: 10 2 8 * + 3 -
I think maybe the tree's order had some problems result in these cases or...
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Nov 13, 2014
So for an assignment I have to write a method that finds that height of this BST. I wrote this:
public int height(Node node)
{
if (node == null)
{
return 0;
}
else
{
return 1 +
Math.max(height(node.left),
height(node.right));
}
}
Which makes sense in my head. However, I added a couple of nodes in and realized I'm not sure how to call this method.
public static void main(String[] args) {
Tree<String, String> tree = new Tree<String, String>();
tree.add("A", "1");//some added stuff
tree.add("B", "2");
tree.add("C", "3");
tree.add("D", "4");
tree.add("E", "5");
tree.add("F", "6");
tree.add("G", "7");
tree.add("H", "8");
System.out.println(tree);
System.out.println(tree.height());
What exactly do I put in the parenthesis after tree.height? If you need to see more of my code I can do that but it is quite lengthy.
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Aug 31, 2014
I'm trying to implement a Binary Search Tree that accepts strings. I cannot figure out how to compare the string value in my add method against the node object. While I could make the node class data be the string type I am trying to make the code be as reusable as possible. So my question is this, is there a simple way I can compare the two that I am missing?
public class BTNode<E> {
private E data;
private BTNode<E> left, right;
//constructor
public BTNode(E initialData, BTNode<E> initialLeft, BTNode<E> initialRight) {
data = initialData;
left = initialLeft;
right = initialRight;
[Code] ....
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Oct 13, 2011
I am trying to make binary search tree...I am trying to construct the left part of binary search tree with root node set as 70...It is not working ...My code is
public class Node {
/**
* @param args
*/
int root;
Node left;
Node right;
public void insertNode(Node node, int num) {
//Node nodeRoot = this;
//root of tree we have set to 70...constructing only left of tree with root=70
[Code] .....
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Oct 4, 2014
Iva tried flipping the entire code upside down (expression) and No matter what I do the delete function returns a null pointer exception after my while loops takes the pointer right to where it should be.
package bp;
import java.time.LocalDate;
public class BinaryTree implements IBinaryTree {
private Node root = null;
private int sizeOfTree = 0;
[Code] ....
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Jun 15, 2014
Here is the problem:
Start with the tree.java program (Listing 8.1) and modify it to create a binary tree from a string of letters (like A, B, and so on) entered by the user. Each letter will be displayed in its own node. Construct the tree so that all the nodes that contain letters are leaves. Parent nodes can contain some non-letter symbol like +. Make sure that every parent node has exactly two children. Don’t worry if the tree is unbalanced. Note that this will not be a search tree; there’s no quick way to find a given node. You may end up with something like this:
It also says all Letters must be Leaves
Now I had it almost similar to that picture, but it wasn't right. So ive been working on it but im getting some very strange (and frustrating) output from the following methods.
Ive included the display method just for reference. The book told me to use it so I haven't edited it. I believe my main issue is with my (incomplete) insert() method. The output goes into an infinite loop despite having a return statement break the while loop when a character is inserted.
The way I see to solve the problem is just add a (+) whenever a new subtree needs to be created. Say I add A and B, then it first creates a subtree at the root with a (+) and afterwards lists A and B as its leaves. If I insert a C, it should be able to simply move to the right child of the root and deposit the C there.
package pkg4333_hwk1;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
class Main {
[Code] ....
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Mar 23, 2014
package SystemandDesign.BinaryTree;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;
import java.io.ObjectInputStream;
[Code] ....
So I am having trouble with trying to get the main method to work. The program is supposed to construct a BinaryTree, and deserialize a file that is used for the Tree.
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Nov 24, 2014
I am trying to draw a binary node tree to a text file.
public class BinaryTreeExample {
public static void main(String[] args) {
new BinaryTreeExample().run();
} static class Node {
Node left;
Node right;
int value;
public Node(int value) {
[Code] .....
This will output:
Building tree with rootvalue25
=================================
Inserted 11 to left of node 25
Inserted 15to right of node 11
Inserted 16to right of node 15
Inserted 23to right of node 16
Inserted 79to right of node 25
Traversing tree in order
=================================
Traversed 11
Traversed 15
Traversed 16
Traversed 23
Traversed 25
Traversed 79
I need to print this information in the form of a graphic to a text file. so for example:
OUTPUT IN TEXT FILE
25
/
11 79
etc...
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May 8, 2015
The purpose of this function is to use a Movie object and a binary search tree to find all movies that have been read in through a file that have a certain rating (G,PG,PG-13,R). The error I am getting is that it seems I am not traversing fully through the tree and therefore only some movies with the rating I search for are output, not all of them with that rating. I have tried figuring out why this is happening and at first I thought my tree was unbalanced, but I am sure it is simply because I am not traversing the tree correctly. I think my implementation in the main is close to what I need but it needs some tweaking. This is my BST class which I created and required to use for this purpose.
public class BinarySearchTree {
/**
* The head of the tree.
*/
private Node root;
/**
* Constructor that declares the head of tree to null.
*/
public BinarySearchTree() {
root = null;
}
/**
* Returns null if head of tree is empty.
* @return null if head of tree is empty.
*/
public boolean isEmpty(){
[Code]...
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Apr 1, 2015
So in my binary search tree I'm trying to write a method that deletes the idem but for some reason it's not working. I have two things, I have the method and then another piece of code that tests the deletion method. Here's the actual method
public void delete(String word) {
root = deleteItem(root, word);
}
protected TreeNode deleteItem(TreeNode r, String word) {
if (r == null){
return r;
}
if(word.compareTo(r.item.getWord()) < 0){
[Code]...
Here's the test code
message = "Test: deleting 'word' -- ";
t = new BSTRefBased();
try {
t.delete("word");
result = t.getRootItem().getWord().equals(null);
} catch (Exception e) {
result = false;
}
System.out.println(message + (result ? "passed" : "FAILED"));
So for some reason it keeps saying that the test failed. Why does it keep saying that.
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Feb 10, 2015
the problem was :
i wrote it on paper with my examples.and just for laughts , i uploaded another picture that dont belong to my problem. its just my way to understand binary search tree implementation , so i wanted so share.just for laught : looks like the map of the universe.
now my problem : why after i changed Current to Current.left, Parent still has the value of root. i draw and wrote it on a paper. to be clear as possible - picture 2 :
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