C++ Programming Exercise: Implement a function Node * buildTree(int nums[], int

Question

C++ Programming Exercise:

Implement a function Node * buildTree(int nums[], int length); that returns a pointer to the root of a balanced binary search tree containing the same values as nums. Assume that the values in nums are all distinct.

Hint: One approach is to sort the array first and then recursively create trees with the middle element of each subarray as the root. If you're worried about efficiency, use an nlogn sorting algorithm. Then creating the BST will be nlogn. You can't do better than that.

Explanation / Answer

class Node
{
    Integer data;
    Node left;
    Node right;
    Node()
    {
        data = null;
        left = null;
        right = null;
    }
}
class BinaryTree
{
    Node head;
    Scanner input = new Scanner(System.in);
    BinaryTree()
    {
        head = null;
    }
    public void createNode(Node temp, Integer value)
    {
        Node newnode= new Node();
        value = getData();
        newnode.data = value;
        temp = newnode;
        if(head==null)
        {
            head = temp;
        }
        System.out.println("If left child exits for ("+value+") enter y else n");
        if(input.next().charAt(0)=='y')
        {
            createNode(temp.left, value);
        }
        System.out.println("If right child exits for ("+value+") enter y else n");
        if(input.next().charAt(0)=='y')
        {
            createNode(temp.right, value);
        }     
    }
    public Integer getData()
    {
        out.println("Enter the value to insert:");
        return (Integer)input.nextInt();
    }

    public void print()
    {
        inorder(head);
    }
    public void inorder(Node node)
    {
        if(node!=null)
        {
            inorder(node.left);
            System.out.println(node.data);
            inorder(node.right);
        }
        else
            return;
    }
}

class BinaryTreeWorker
{
    static BinaryTree treeObj = null;
    static Scanner input = new Scanner(System.in);
    public static void displaymenu()
    {
        int choice;
        do{
            out.print(" Basic operations on a tree:");
            out.print(" 1. Create tree 2. Insert 3. Search value 4. print list Else. Exit Choice:");
            choice = input.nextInt();

            switch(choice)
            {
                case 1:
                    treeObj = createBTree();
                    break;
                case 2:
                    treeObj.createNode(null, null);
                    break;
                case 3:
                    //searchnode();
                    break;
                case 4:
                    treeObj.print();
                    break;
                default:
                    return;
            }     
        }while(true);
    }
    public static BinaryTree createBTree()
    {
        return new BinaryTree();
    }
    public static void main(String[] args)
    {
        displaymenu();
    }
}

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