剑指offer_23

题意：层序打印二叉树
思路：维护一个队列，存储二叉树从上至下、从左至右的打印顺序，先进先出。
代码：

package MianShiTi_23;

import java.util.LinkedList;
import java.util.Queue;

import javax.swing.text.AbstractDocument.LeafElement;

public class MianShiTi_23 {
    public static class binaryTree {
        int value;
        binaryTree leftChild;
        binaryTree rightChild;
    }
    public static void layerTraversal(binaryTree node) {
        if(node == null){return;}
        //linkedlist实现了queue。
        Queue<binaryTree> queue = new LinkedList<>();
        queue.add(node);
        while (queue.size() != 0) {
            binaryTree pnode = queue.poll();
            System.out.print(pnode.value+"->");
            if(pnode.leftChild != null){
                queue.add(pnode.leftChild);
            }
            if(pnode.rightChild != null){
                queue.add(pnode.rightChild);
            }
        }

    }
    public static void main(String[] args) {
        binaryTree node = new binaryTree();
        node.value = 8;
        node.leftChild = new binaryTree();
        node.leftChild.value = 6;
        node.rightChild = new binaryTree();
        node.rightChild.value = 10;
        node.leftChild.leftChild = new binaryTree();
        node.leftChild.leftChild.value = 5;
        node.leftChild.rightChild = new binaryTree();
        node.leftChild.rightChild.value = 7;
        node.rightChild.leftChild = new binaryTree();
        node.rightChild.leftChild.value = 9;
        node.rightChild.rightChild = new binaryTree();
        node.rightChild.rightChild.value = 11;
        new MianShiTi_23().layerTraversal(node);
    }

}