剑指offer面试题23-从上往下打印二叉树

public class BinaryTreeNode {
	Integer value;
	BinaryTreeNode left;
	BinaryTreeNode right;

	public BinaryTreeNode(Integer value) {
		this.value = value;
	}

	@Override
	public String toString() {
		return "BinaryTreeNode [value=" + value + "]";
	}

}

/**
 * 从上往下打印出二叉树的每个节点，每一层的节点展昭从左到右的顺序打印。<br/>
 * 即树的广度遍历
 * */
public class PrintFromTopToBottom {

	public void print(BinaryTreeNode root) {
		if (root == null) {
			return;
		}
		BinaryTreeNode current = root;
		Queue<BinaryTreeNode> children = new LinkedList<BinaryTreeNode>();
		while (current != null) {
			System.out.println(current);
			if (current.left != null) {
				children.offer(current.left);
			}
			if (current.right != null) {
				children.offer(current.right);
			}
			if (children.isEmpty()) {
				break;
			} else {
				current = children.poll();
			}
		}
	}
}