public final class BinaryTrees {
	// 打印一棵二叉树
	public static void print(BinaryTreeInfo tree);
	public static void print(BinaryTreeInfo tree, PrintStyle style);

	// 打印一棵二叉树（打印完自动换行）
	public static void println(BinaryTreeInfo tree);
	public static void println(BinaryTreeInfo tree, PrintStyle style);

	// 获得一棵二叉树的打印字符串
	public static String printString(BinaryTreeInfo tree);
	public static String printString(BinaryTreeInfo tree, PrintStyle style);

	// 可选的打印样式
	public enum PrintStyle {
		LEVEL_ORDER, 
		INORDER
	}
}

/**
* BinarySearchTree是你自己编写的二叉树类
* BinarySearchTree is a binary tree class that is created by yourself.
*/
public class BinarySearchTree<E> implements BinaryTreeInfo {
	/**这里省略了大量代码，只贴出了脉络代码**/
	/** only show some main code **/
	
	private Node<E> root;
	private static class Node<E> {
		E element;
		Node<E> left;
		Node<E> right;
	}
	
	/********** BinaryTreeInfo **********/
	@Override
	public Object root() {
		// 根节点是谁？
		// who is the root node?
		return root;
	}

	@Override
	public Object left(Object node) {
		// 如何查找左节点？
		// how to get the left child of the node?
		return ((Node)node).left;
	}

	@Override
	public Object right(Object node) {
		// 如何查找右节点？
		// how to get the right child of the node?
		return ((Node)node).right;
	}

	@Override
	public Object string(Object node) {
		// 如何打印单个节点？
		// how to print the node?
		return ((Node)node).element;
	}
	/********** BinaryTreeInfo **********/
}

// 随机生成的一棵二叉搜索树（random generation）
BinarySearchTree<Integer> bst = ...;

// PrintStyle.LEVEL_ORDER（层序打印）
BinaryTrees.println(bst); 

// PrintStyle.INORDER（中序打印）
BinaryTrees.println(bst, PrintStyle.INORDER);

Files.writeToFile("F:/test/bst.txt", BinaryTrees.printString(bst));

BinaryTrees.println(new BinaryTreeInfo() {
	@Override
	public Object root() {
		return 8;
	}

	@Override
	public Object left(Object node) {
		if (node.equals(8)) return 3;
		if (node.equals(3)) return 1;
		if (node.equals(6)) return 4;
		if (node.equals(14)) return 13;
		return null;
	}

	@Override
	public Object right(Object node) {
		if (node.equals(8)) return 10;
		if (node.equals(10)) return 14;
		if (node.equals(3)) return 6;
		if (node.equals(6)) return 7;
		return null;
	}
	
	@Override
	public Object string(Object node) {
		return node;
	}
});

BinaryTrees.println(new BinaryTreeInfo() {
	@Override
	public Object root() {
		return "Life";
	}
	
	@Override
	public Object left(Object node) {
		if (node.equals("Life")) return "Animal";
		if (node.equals("Person")) return "Man";
		if (node.equals("Animal")) return "Cat";
		if (node.equals("Dog")) return "Teddy";
		return null;
	}
	
	@Override
	public Object right(Object node) {
		if (node.equals("Life")) return "Person";
		if (node.equals("Person")) return "Woman";
		if (node.equals("Animal")) return "Dog";
		if (node.equals("Dog")) return "SingleDog";
		return null;
	}
	
	@Override
	public Object string(Object node) {
		return node;
	}
});

public class BinaryHeap<E> implements BinaryTreeInfo {
	private int size;
	private E[] elements;

	@Override
	public Object root() {
		return 0;
	}

	@Override
	public Object left(Object node) {
		int index = ((int)node << 1) + 1;
		return index >= size ? null : index;
	}

	@Override
	public Object right(Object node) {
		int index = ((int)node << 1) + 2;
		return index >= size ? null : index;
	}

	@Override
	public Object string(Object node) {
		return elements[(int)node];
	}
}

BinaryHeap<Integer> heap = new BinaryHeap<>();
for (int i = 0; i < 10; i++) {
	heap.add((int)(Math.random() * 100));
}
BinaryTrees.println(heap);