DS-A/Binary search tree using recursion at main · Kathircpe/DS-A · GitHub

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public class main {

    public static  void main(String[] args) {

        binarySearchTree tree=new binarySearchTree();

        tree.insert(5);
        tree.insert(4);
        tree.insert(6);
        tree.insert(2);
        tree.insert(8);
        tree.insert(9);
        tree.insert(7);
        tree.insert(1);
        tree.insert(3);

        tree.remove(5);

        tree.display();

//        System.out.println(tree.search(1));

    }
public class binarySearchTree {

    Node root;

    public void insert(int data) {
        root = insertHelper(root, new Node(data));
    }

    private Node insertHelper(Node root, Node node) {

        int data = node.data;

        if (root == null) {
            root = node;
            return root;
        } else if (data < root.data) {
            root.left = insertHelper(root.left, node);

        } else {
            root.right = insertHelper(root.right, node);
        }
        return root;
    }

    public void display() {

        displayHelper(root);
    }

    private void displayHelper(Node root) {

        if (root != null) {
            displayHelper(root.left);
            System.out.println(root.data);
            displayHelper(root.right);
        }
    }

    public boolean search(int data) {

        return searchHelper(root, data);
    }

    private boolean searchHelper(Node root, int data) {
        if (root == null) {
            return false;
        } else if (data == root.data) {
            return true;
        } else if (root.data > data) {
            return searchHelper(root.left, data);
        } else {
            return searchHelper(root.right, data);
        }

    }

    public void remove(int data) {

        if (search(data)) {
            removeHelper(root, data);
        } else {
            System.out.println(data + " Could not found in the data");
        }
    }

    private Node removeHelper(Node root, int data) {

        if (root == null) {
            return root;
        } else if (data < root.data) {
            root.left = removeHelper(root.left, data);
        } else if (data > root.data) {
            root.right = removeHelper(root.right, data);

        } else { // Node found
            if (root.left == null && root.right == null) {
                root = null;
            } else if (root.right != null) {
                root.data = successor(root);
                root.right = removeHelper(root.right, root.data);
            } else {
                root.data = predecessor(root);
                root.left = removeHelper(root.left, root.data);
            }

        }
        return root;

    }

    private int successor(Node root) {

        root = root.right;

        while (root.left != null) {
            root = root.left;
        }

        return root.data;
    }

    private int predecessor(Node root) {
        root = root.left;

        while (root.right != null) {
            root = root.right;
        }

        return root.data;
    }
}
public class Node {
    int data;
    Node left;
    Node right;
    Node(int data){
        this.data=data;
    }
}


}