- Implement the size() method (along with a recursive method) for the BinarySearchTree class developed in lecture.

- Implement the contains() method (along with a recursive method) for the BinarySearchTree class developed in lecture.

- Implement the toString() method (along with a recursive method) for the BinarySearchTree class developed in lecture that returns a string containing all of the elements in sorted order.

- Implement a recursive method, max() that returns the largest value of the tree.

- Implement a recursive method, min() that returns the smallest value of the tree.

**This is what we implemented in class

public class BinarySearchTree> { private static class Node { E value; Node lKid; Node rKid; Node(E value) { this(value, null, null); }

Node(E value, Node left, Node right) { this.value = value; lKid = left; rKid = right; } }

private Node root;

public boolean isEmpty() { return root==null; }

public int size() { return size(root); }

private int size(Node subroot) { int size = 0; if(subroot!=null) { size = 1 + size(subroot.lKid) + size(subroot.rKid); } return size; }

public boolean add(E value) { if(value==null) { throw new NullPointerException("Nulls not welcome here"); } boolean isChanged; if(root==null) { root = new Node<>(value); isChanged = true; } else { isChanged = add(root, value); } return isChanged; }

private boolean add(Node subroot, E value) { boolean isChanged = false; int comparison = value.compareTo(subroot.value); if(comparison>0) { if(subroot.rKid==null) { subroot.rKid = new Node<>(value); isChanged = true; } else { isChanged = add(subroot.rKid, value); } } else if(comparison<0) { if(subroot.lKid==null) { subroot.lKid = new Node<>(value); isChanged = true; } else { isChanged = add(subroot.lKid, value); } } return isChanged; } }