Question

java A University would like to implement its students registery as a binary search tree, calledStudentBST. Write an Student node class, called StudentNode, to hold the following information about an Student: - id (as a int) - gpa (as double) StudentNode should have constructors and methods (getters, setters, and toString()) to manage Write the StudentBST class, which is a binary search tree to hold objects of the class StudentNode. The key in each node is the id. :

import.java.ArrayList; public void addStudent(StudentNode sn){}

// adds a Student at the front of the list public ArrayList preorderTraversal(){}

//preorder traversal by returning an arraylist of visited student nodes public ArrayList inorderTraversal(){}

//inorder traversal by returning an array of visited student nodes public ArrayList postorderTraversal(){}

//postorder traversal by returning an array of visited student nodes public int gpaGreaterThan(double a);

// method that returns the number of StudentNode objects having their gpa greater than a (hint: use the result of one of traversal algorithms)

Answer 1

Please find the code below:

StudentBST.java

package bstnew;

import java.util.ArrayList;

/* Class containing left and right child of current node and id value*/

class StudentNode

{

int id;

double gpa;

StudentNode left, right;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public double getGpa() {

return gpa;

}

public void setGpa(double gpa) {

this.gpa = gpa;

}

public StudentNode getLeft() {

return left;

}

public void setLeft(StudentNode left) {

this.left = left;

}

public StudentNode getRight() {

return right;

}

public void setRight(StudentNode right) {

this.right = right;

}

public StudentNode(int id, double gpa) {

super();

this.id = id;

this.gpa = gpa;

}

@Override

public String toString() {

return "StudentNode [id=" + id + ", gpa=" + gpa + "]";

}

}

//Java program to demonstrate delete operation in binary search tree

class StudentBST

{

// Root of BST

StudentNode root;

// Constructor

StudentBST()

{

root = null;

}

public void addStudent(StudentNode sn){

root=insertRec(root,sn);

}

StudentNode insertRec(StudentNode root, StudentNode sn)

{

if (root == null)

{

root = sn;

return root;

}

if (sn.id < root.id)

root.left = insertRec(root.left, sn);

else if (sn.id > root.id)

root.right = insertRec(root.right, sn);

return root;

}

ArrayList<StudentNode> inorderTraversal(){

ArrayList<StudentNode> nodeList = new ArrayList<>();

inorderTraversal(root,nodeList);

return nodeList;

}

void inorderTraversal(StudentNode root,ArrayList<StudentNode> nodeList)

{

if (root != null)

{

inorderTraversal(root.left,nodeList);

nodeList.add(root);

inorderTraversal(root.right,nodeList);

}

}

ArrayList<StudentNode> preorderTraversal(){

ArrayList<StudentNode> nodeList = new ArrayList<>();

preorderTraversal(root,nodeList);

return nodeList;

}

void preorderTraversal(StudentNode root,ArrayList<StudentNode> nodeList)

{

if (root != null)

{

nodeList.add(root);

preorderTraversal(root.left,nodeList);

preorderTraversal(root.right,nodeList);

}

}

ArrayList<StudentNode> postTraversal(){

ArrayList<StudentNode> nodeList = new ArrayList<>();

postTraversal(root,nodeList);

return nodeList;

}

void postTraversal(StudentNode root,ArrayList<StudentNode> nodeList)

{

if (root != null)

{

postTraversal(root.left,nodeList);

postTraversal(root.right,nodeList);

nodeList.add(root);

}

}

int gpaGreaterThan(double a){

int count=0;

ArrayList<StudentNode> list = postTraversal();

for(StudentNode s : list){

if(s.gpa>a){

count++;

}

}

return count;

}

public static void main(String[] args)

{

StudentBST tree=new StudentBST();

StudentNode student1 = new StudentNode(1, 90);

StudentNode student2 = new StudentNode(5, 80);

StudentNode student3 = new StudentNode(2, 100);

StudentNode student4 = new StudentNode(4, 30);

StudentNode student5 = new StudentNode(3, 40);

tree.addStudent(student1);

tree.addStudent(student2);

tree.addStudent(student3);

tree.addStudent(student4);

tree.addStudent(student5);

System.out.println("Record Inorder");

for(StudentNode s : tree.inorderTraversal()){

System.out.println(s);

}

System.out.println();

System.out.println("Record PreOrder");

for(StudentNode s : tree.preorderTraversal()){

System.out.println(s);

}

System.out.println();

System.out.println("Record PostOrder");

for(StudentNode s : tree.postTraversal()){

System.out.println(s);

}

int count = tree.gpaGreaterThan(70);

System.out.println("\nStudent count with gpa greater than 70 is : "+count);

}

}

output:

$Console 3 rminated> StudentBST Java Application] C:\Program Files Javare7\bin javaw.exe (De Record Inorder StudentNode id-1, apa-90.01 StudentNode [id-2, gpa-100.0] StudentNode [id-3, gpa-40.0] StudentNode [id-4, gpa 30.0] StudentNode [id-5, gpa-80.0] Record PreOrder StudentNode [id-l, gpa-90.0] StudentNode [id-5, gpa-80.0] StudentNode [id-2, gpa-100.0] StudentNode [id-4, gpa 30.0] StudentNode [id-3, gpa-40.0] Record PostOrder StudentNode [id-3, gpa-40.0] StudentNode [id-4, gpa 30.0] StudentNode [id-2, gpa-100.0] StudentNode [id-5, gpa-80.0] StudentNode [id-l, gpa-90.0] Student count with gpa greater than 70 is : 3$