Amorphous-Binary-Tree-Creator--Binary-Tree/BTreePrinter.java at master · JoeAzar/Amorphous-Binary-Tree-Creator--Binary-Tree · GitHub

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/**
 * @author Michal Kreuzman
 *
 * Pulled from StackOverflow
 */
public class BTreePrinter
{

	public static <T> void printNode(TreeNode<T> root)
	{
		int maxLevel = BTreePrinter.maxLevel(root);

		printNodeInternal(Collections.singletonList(root), 1, maxLevel);
	}

	private static <T> void printNodeInternal(List<TreeNode<T>> nodes, int level, int maxLevel)
	{
		if (nodes.isEmpty() || BTreePrinter.isAllElementsNull(nodes))
			return;

		int floor = maxLevel - level;
		int endgeLines = (int) Math.pow(2, (Math.max(floor - 1, 0)));
		int firstSpaces = (int) Math.pow(2, (floor)) - 1;
		int betweenSpaces = (int) Math.pow(2, (floor + 1)) - 1;

		BTreePrinter.printWhitespaces(firstSpaces);

		List<TreeNode<T>> newNodes = new ArrayList<TreeNode<T>>();
		for (TreeNode<T> node : nodes)
		{
			if (node != null)
			{
				System.out.print(node.self);
				newNodes.add(node.getLeftChild());
				newNodes.add(node.getRightChild());
			}
			else
			{
				newNodes.add(null);
				newNodes.add(null);
				System.out.print(" ");
			}

			BTreePrinter.printWhitespaces(betweenSpaces);
		}
		System.out.println("");

		for (int i = 1; i <= endgeLines; i++)
		{
			for (int j = 0; j < nodes.size(); j++)
			{
				BTreePrinter.printWhitespaces(firstSpaces - i);
				if (nodes.get(j) == null)
				{
					BTreePrinter.printWhitespaces(endgeLines + endgeLines + i + 1);
					continue;
				}

				if (nodes.get(j).getLeftChild() != null)
					System.out.print("/");
				else
					BTreePrinter.printWhitespaces(1);

				BTreePrinter.printWhitespaces(i + i - 1);

				if (nodes.get(j).getRightChild() != null)
					System.out.print("\\");
				else
					BTreePrinter.printWhitespaces(1);

				BTreePrinter.printWhitespaces(endgeLines + endgeLines - i);
			}

			System.out.println("");
		}

		printNodeInternal(newNodes, level + 1, maxLevel);
	}

	private static void printWhitespaces(int count)
	{
		for (int i = 0; i < count; i++)
			System.out.print(" ");
	}

	private static <T> int maxLevel(TreeNode<T> node)
	{
		if (node == null)
			return 0;

		return Math.max(BTreePrinter.maxLevel(node.getLeftChild()), BTreePrinter.maxLevel(node.getRightChild())) + 1;
	}

	private static <T> boolean isAllElementsNull(List<T> list)
	{
		for (Object object : list)
		{
			if (object != null)
				return false;
		}

		return true;
	}

}