Bidirectional Binary Tree

BidirectionalBinaryTree.java

package br.com.uol.ps.so.api;

import java.util.ArrayList;
import java.util.List;

import lombok.AllArgsConstructor;
import lombok.Data;

/**
 * @author Julio Falbo
 * @version $Revision: $<br/>
 * $Id: $
 * @since 12/12/18 09:17
 */
public class Main {

    static List<Tree> database = new ArrayList<>();

    public static void main(String[] args) {
        createTree(null, false, true);
        createTree(1, false, true);
        createTree(3, true, false);
        changeParent(5, 4);
    }

    @Data
    @AllArgsConstructor
    static
    class Tree {

        Integer id;

        Integer idParent;

        Integer idRight;

        Integer idLeft;
    }

    private static void createTree(Integer parentId, Boolean hasRight, Boolean hasLeft) {
        final Tree root = new Tree(database.size() + 1, parentId, null, null);
        database.add(root);
        if (hasRight) {
            final Tree right = new Tree(database.size() + 1, root.getId(), null, null);
            database.add(right);
            database.get(root.getId() - 1).setIdRight(right.getId());
        }
        if (hasLeft) {
            final Tree left = new Tree(database.size() + 1, root.getId(), null, null);
            database.add(left);
            database.get(root.getId() - 1).setIdLeft(left.getId());
        }
        if (parentId != null) {
            final Tree tree = database.get(parentId - 1);
            insertNodeInEmptySpace(tree, root.getId());
        }
    }

    private static void insertNodeInEmptySpace(final Tree tree, final Integer id) {
        if (tree.getIdLeft() != null && tree.getIdRight() != null) {
            throw new RuntimeException("Parent tree is full");
        }
        if (tree.getIdLeft() == null) {
            tree.setIdLeft(id);
        } else if (tree.getIdRight() == null) {
            tree.setIdRight(id);
        }
    }

    private static void changeParent(Integer currentTreeId, Integer newParentId) {
        final Tree currentTree = database.get(currentTreeId - 1);

        final Tree oldParent = database.get(currentTree.getIdParent() - 1);
        if (oldParent.getIdLeft() != null && oldParent.getIdLeft().equals(currentTreeId)) {
            oldParent.setIdLeft(null);
        }
        if (oldParent.getIdRight() != null && oldParent.getIdRight().equals(currentTreeId)) {
            oldParent.setIdRight(null);
        }

        final Tree newParent = database.get(newParentId - 1);
        insertNodeInEmptySpace(newParent, currentTreeId);

        currentTree.setIdParent(newParentId);
    }

}