C# Binary Search Tree giving Incorrect Majority Element

Question

The main reason I'm using the BST is to get the Majority Element, being the Value > Array.Length / 2.

So, if we have an array of 5 elements, there must be a minimum of at least 3 to be considered the majority.

Now the problem I am facing at the moment is that the Majority Element is being chosen for whichever element is first in the Array.

This is the code below:

public Node nnde(Node root)
{               
    if (root== null)
    {
        root= newNode;
        size++;
        return root;
    }

    if (elm < root.elm)
    {
        if (root.lft != null)
        {
            InsertNewNode(root.lft, elm);
        }
        else
        {
            root.lft = new Node(elm);
        }
    }
    else if (elm> root.rght)
    {
        if (root.rght != null)
        {
            InsertNewNode( root.rght, elm);
        }
        else
        {
            root.rght = new Node(elm);
        }
    }

    return root;
}

Elements in the array: 2 0 1 2 1

There should be no majority element, however, the BST I currently programmed is showing it as 2.

You have to call the method GetMajorityElement for each unique value in the array and then compare which gives the largest return value. — jdweng, May 27 '18 at 09:42
The code is not posted. That is where the error probably lies. — jdweng, May 27 '18 at 10:37
In your method `InsertNewNode`, you are not updating the `size` property properly. With this code the size of your tree will be 2, which is why it is returning majority as 2 — Aman B, May 27 '18 at 11:40

user7943 · Accepted Answer · 2018-05-29T09:01:28.300

After some time trying to figure out what the problem could actually be, the realization that I had forgotten to insert a simple size++ in the InsertNewNode() method came to me.

Code edited is as follows:

        if (elm <  root.lft)
        {
            if (root.lft != null)
            {
                root.lft = InsertNewNode(root.lft, elm);
            }
            else
            {
                root.lft = new Node(elm);
                size++;
            }
        }
        else if (elm > root.rght)
        {
            if (root.rght != null)
            {
                root.rght = InsertNewNode(root.rght, elm);
            }
            else
            {
                root.rght = new Node(elm);
                size++;
            }
        }

C# Binary Search Tree giving Incorrect Majority Element

1 Answers1