Find maximum product of K integers in a Binary Search Tree

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

// Define a class for the BST node
class Node {
    public int value;
    public Node left;
    public Node right;

    public Node(int val) {
        value = val;
        left = null;
        right = null;
    }
}

public class MaximumProductBST {
    // Function to traverse the BST in any
    // order and store the nodes in a list
    static void traverse(Node root, List<Node> nodes) {
        if (root == null) {
            return;
        }
        traverse(root.left, nodes);
        nodes.add(root);
        traverse(root.right, nodes);
    }

    // Function to sort the list in
    // decreasing order of node values
    static Comparator<Node> comparator = (a, b) -> b.value - a.value;

    // Function to compute the product
    // of k nodes
    static int product(List<Node> nodes, int k) {
        int prod = 1;
        for (int i = 0; i < k; i++) {
            prod *= nodes.get(i).value;
        }
        return prod;
    }

    // Function to find the maximum product
    // of k nodes in the BST
    static int maxProduct(Node root, int k) {
        // Create a list to store the nodes
        List<Node> nodes = new ArrayList<>();

        // Traverse the BST and store the
        // nodes in the list
        traverse(root, nodes);

        // Sort the list in decreasing
        // order of node values
        Collections.sort(nodes, comparator);

        // If the number of nodes in the
        // BST is less than k, return 0
        if (nodes.size() < k) {
            return 0;
        }

        // Compute the product of the first
        // k nodes in the sorted list
        int prod = product(nodes, k);

        // Return the product
        return prod;
    }

    // Driver code
    public static void main(String[] args) {
        // Create the BST
        /*
                 10
                /  \
               3    12
              / \   / \
             2   4 11  13
        */
        Node root = new Node(10);
        root.left = new Node(3);
        root.right = new Node(12);
        root.left.left = new Node(2);
        root.left.right = new Node(4);
        root.right.left = new Node(11);
        root.right.right = new Node(13);

        // Function call
        System.out.println(maxProduct(root, 3));
    }
}
// This code was contributed by codearcade