package books;

import java.util.concurrent.LinkedBlockingQueue;

/**

* @program JavaBooks

* @description: 从上到下打印二叉树

* @author: mf

* @create: 2019/09/13 12:38

*/

/*

不分行从下到上打印二叉树

从上到下打印出二叉树的每个节点，同一层的节点按照从左到右的顺序打印

例如，见书

*/

/*

思路

这个题需要辅助队列容器

也就是说， 从上往下打印某个节点时，该节点的两个子节点不为空，就加进容器中，

直到打印到容器为空为止。

*/

public class T32 {

public static void main(String[] args) {

int[] pre = {8, 6, 5, 7, 10, 9, 11};

int[] in = {5, 6, 7, 8, 9, 10, 11};

TreeNode node = TreeNode.setBinaryTree(pre, in);

// printNode(node);

printNode2(node);

}

private static void printNode(TreeNode node) {

if (node == null) return;

// new一个队列

LinkedBlockingQueue<TreeNode> queue = new LinkedBlockingQueue<>();

queue.offer(node);

while (!queue.isEmpty()) {

TreeNode tempNode = queue.poll();

System.out.print(tempNode.val + "\t");

if (tempNode.left != null) {

queue.offer(tempNode.left);

}

if (tempNode.right != null) {

queue.offer(tempNode.right);

}

}

}

// 分行打印

private static void printNode2(TreeNode node) {

if (node == null) return;

LinkedBlockingQueue<TreeNode> queue = new LinkedBlockingQueue<>();

queue.offer(node);

int cLevel = 1;

int nextLevel = 0;

while (!queue.isEmpty()) {

TreeNode tempNode = queue.poll();

System.out.print(tempNode.val + "\t");

cLevel--;

if (tempNode.left != null) {

queue.offer(tempNode.left);

nextLevel++;

}

if (tempNode.right != null) {

queue.offer(tempNode.right);

nextLevel++;

}

if (cLevel == 0) {

System.out.print("\n");

cLevel = nextLevel;

nextLevel = 0;

}

}

}

}