import java.util.LinkedList;

import java.util.List;

/**

* Author: 王俊超

* Date: 2015-06-16

* Time: 17:12

* Declaration: All Rights Reserved !!!

*/

public class Test60 {

private static class BinaryTreeNode {

private int val;

private BinaryTreeNode left;

private BinaryTreeNode right;

public BinaryTreeNode() {

}

public BinaryTreeNode(int val) {

this.val = val;

}

@Override

public String toString() {

return val + "";

}

}

/**

* 题目：从上到下按层打印二叉树，同一层的结点按从左到右的顺序打印，每一层打印一行。

* @param root

*/

public static void print(BinaryTreeNode root) {

if (root == null) {

return;

}

List<BinaryTreeNode> list = new LinkedList<>();

BinaryTreeNode node;

// 当前层的结点个数

int current = 1;

// 记录下一层的结点个数

int next = 0;

list.add(root);

while (list.size() > 0) {

node = list.remove(0);

current--;

System.out.printf("%-3d", node.val);

if (node.left != null) {

list.add(node.left);

next++;

}

if (node.right != null) {

list.add(node.right);

next++;

}

if (current ==0) {

System.out.println();

current = next;

next = 0;

}

}

}

public static void main(String[] args) {

BinaryTreeNode n1 = new BinaryTreeNode(1);

BinaryTreeNode n2 = new BinaryTreeNode(2);

BinaryTreeNode n3 = new BinaryTreeNode(3);

BinaryTreeNode n4 = new BinaryTreeNode(4);

BinaryTreeNode n5 = new BinaryTreeNode(5);

BinaryTreeNode n6 = new BinaryTreeNode(6);

BinaryTreeNode n7 = new BinaryTreeNode(7);

BinaryTreeNode n8 = new BinaryTreeNode(8);

BinaryTreeNode n9 = new BinaryTreeNode(9);

n1.left = n2;

n1.right = n3;

n2.left = n4;

n2.right = n5;

n3.left = n6;

n3.right = n7;

n4.left = n8;

n4.right = n9;

print(n1);

}

}