Question

Java:

Create a BST with input keys S E X R A C. (Assume the values are 1,2,3,4,5,6, resp.)

Answer 1

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JAVA PROGRAM

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///////////////BST.java/////////////////

//Class: BST

public class BST {

/**

*inner class Node

*/

class Node {

String key;

int value;

Node left;

Node right;

//constructor

public Node(String key,int value){

this.key = key;

this.value = value;

}

@Override

public String toString() {

return "Node [key=" + key + ", value=" + value + "]";

}

}

private Node root;

/**

* public method insert

* It will call insertKey method

* by passing root node along with key and value

* @param key

* @param value

*/

public void insert(String key,int value){

root = insertKey(root,key,value);

}

/**

* private recursive method insertKey

* It will insert the node at its proper position

* in binary search tree

* @param node

* @param key

* @param value

* @return

*/

private Node insertKey(Node node, String key,int value){

if(node == null){//if node is null

return new Node(key,value);//return a new Node

}

//compare current key , with key of current node

int compareValue = key.compareTo(node.key);

if(compareValue < 0)//if it is lesser

node.left = insertKey(node.left,key,value);//insert key in left child

else if(compareValue > 0)//if it is greater

node.right = insertKey(node.right,key,value);//insert key at right child

else //if it is same

node.value = value;//update the value

return node;

}

/**

* public method printTree

* It will call private method print

* by passing root Node

*/

public void printTree(){

System.out.println("Traversing Binary search Tree In-order:");

print(root);

}

/**

* print tree with in-order traversal

* this is a recursive method

* @param node

*/

private void print(Node node){

if(node ==null)

return;

//print inOrder

print(node.left);//left child

System.out.println(node);//print node

print(node.right);//right child

}

}

/////////////////////TestBST.java//////////////////////

//Test class: TestBST

public class TestBST{

//main method

public static void main(String[] args){

BST bst = new BST();//create a new instance of BST

//insert keys as given with their values

bst.insert("S", 1);

bst.insert("E", 2);

bst.insert("X", 3);

bst.insert("R", 4);

bst.insert("A", 5);

bst.insert("C", 6);

//finally print the Binary search tree with

//inserted nodes in-order

bst.printTree();

}

}

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OUTPUT

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Traversing Binary search Tree In-order:

Node [key=A, value=5]

Node [key=C, value=6]

Node [key=E, value=2]

Node [key=R, value=4]

Node [key=S, value=1]

Node [key=X, value=3]