从上往下打印二叉树

题目描述
从上往下打印出二叉树的每个节点，同层节点从左至右打印。

import java.util.ArrayList;
/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
            ArrayList<TreeNode>  listNode=new ArrayList<TreeNode> ();
        ArrayList<Integer>  listVal=new ArrayList<Integer> ();
        if(root==null)
            return listVal;
        listNode.add(root);
        listVal.add(root.val);
        for(int i=0;i<listNode.size();i++){
          TreeNode node=  listNode.get(i);
            if(node.left!=null){
                listNode.add(node.left);
                listVal.add(node.left.val);
            }
            if(node.right!=null){
                listNode.add(node.right);
                  listVal.add(node.right.val);
        }

        }

        return listVal;
    }

}

package com.struct.tree.secondeTree;

import java.util.ArrayList;
import java.util.Stack;

public class Tree
{
    private static final String left = "leftSon";
    private static final String right = "rightSon";
    public static void main(String[] args)
    {
        TreeType treeType = new TreeType();
        treeType.init("A");
        treeType.add("B", "A", left);
        treeType.add("C", "A", right);
        treeType.add("D", "B", left);
        treeType.add("E", "B", right);
        treeType.add("F", "C", left);
        treeType.add("G", "C", right);
        treeType.add("H", "D", left);
        treeType.add("I", "F", right);
        System.out.println("前序遍历：");
        treeType.DLR(treeType.getRoot());
        System.out.println();
        System.out.println("非递归前序遍历： ");
        treeType.iteratorPre(treeType.getRoot());
        System.out.println();
        System.out.println("中序遍历：");
        treeType.LDR(treeType.getRoot());
        System.out.println();
        System.out.println("非递归中序遍历： ");
        treeType.iteratorMid(treeType.getRoot());
        System.out.println();
        System.out.println("后续遍历： ");
        treeType.LRD(treeType.getRoot());
        System.out.println();
        System.out.println("非递归后续遍历： ");
        treeType.iteratorLat(treeType.getRoot());
        System.out.println();
        System.out.println("按层遍历： ");
        treeType.level(treeType.getRoot());
        System.out.println();
        System.out.println("安层遍历2： ");
        treeType.showlevel();
        System.out.println();
        System.out.println("树的深度:");
        //树的深度
        System.out.println(treeType.dept(treeType.getRoot()));
    }

}

class Node{
    private Object value;   //结点数据
    private Node left;  //左指针
    private Node right; //右指针
    public Node(Object va)
    {
        this.value = va;
        left = null;
        right = null;
    }

    public Object getValue(){
        return value;
    }

    public Node getLeft(){
        return this.left;
    }

    public void setLeft(Node node){
        this.left = node;
    }

    public Node getRight(){
        return this.right;
    }

    public void setRight(Node node){
        this.right = node;
    }

}

class TreeType{
    private Node root;
    private static int MaxLen=20;
    public Node init(Object val){
            root = new Node(val);
            return root;
    }

    public Node getRoot(){
        return root;
    }

    public void add(Object val,Object parent,String direction){

        Node parentNode=getParent(root, parent);
        Node newNode = new Node(val);
        if(parentNode==null){
            System.out.println("what your insert is wrong");
            return;
        }

        switch (direction)
        {
            case "leftSon":
                if(parentNode.getLeft()!=null){
                    System.out.println("leftson is not null");
                }
                parentNode.setLeft(newNode);
                break;
            case "rightSon":
                if(parentNode.getRight()!=null){
                    System.out.println("rightson is not null");
                }
                parentNode.setRight(newNode);                
                break;
        }
    }

    public Node getParent(Node root,Object parent){

        Node p;
        Node temp = root;
        if(root==null){
            return null;
        }else {
            if(temp.getValue().equals(parent)){
                return temp;
            }else if ((p=getParent(temp.getLeft(), parent))!=null) {
                return p;
            }else if ((p=getParent(temp.getRight(), parent))!=null) {
                return p;
            }else {
                return null;
            }
        }
    }

    //显示节点
    public void show(Node parentNode){
        if(parentNode==null){
            System.out.println("does not exits");
        }
        System.out.print(parentNode.getValue()+" ");
    }

    //前序遍历
    public void DLR(Node node){
        if(node!=null){
            show(node);
            DLR(node.getLeft());
            DLR(node.getRight());
        }
    }

    //中序遍历
    public void LDR(Node node){
        if(node!=null){
            LDR(node.getLeft());
            show(node);
            LDR(node.getRight());
        }
    }

    //后序遍历
    public void LRD(Node node){
        if(node!=null){
            LRD(node.getLeft());
            LRD(node.getRight());
            show(node);
        }
    }

    //按层遍历
    public void level(Node node){
        Node pNode;
        Node[] q = new Node[MaxLen];
        int head=0;
        int tail=0;
        if(node!=null){
            tail=(tail+1);
            q[tail]=node;
        }
        while(head!=tail){
            head=(head+1);
            pNode=q[head];
            show(pNode);
            if(pNode.getLeft()!=null){
                tail=(tail+1);
                q[tail]=pNode.getLeft();
            }
            if(pNode.getRight()!=null){
                tail=(tail+1);
                q[tail]=pNode.getRight();
            }
        }
    }



    //按曾遍历2
    public static ArrayList<String> PrintFromTopToBottom(Node root) {
            ArrayList<Node>  listNode=new ArrayList<Node> ();
            ArrayList<String>  listVal=new ArrayList<String> ();
            if(root==null)
                return listVal;
            listNode.add(root);
            listVal.add((String) root.getValue());
            for(int i=0;i<listNode.size();i++){
                Node node=  listNode.get(i);
                if(node.getLeft()!=null){
                    listNode.add(node.getLeft());
                    listVal.add((String)node.getLeft().getValue());
                }
                if(node.getRight()!=null){
                    listNode.add(node.getRight());
                      listVal.add((String)node.getRight().getValue());
            }

            }

            return listVal;
        }

      //按曾遍历2
    public void showlevel(){
       ArrayList<String> arrayList = PrintFromTopToBottom(root);
       for(String a:arrayList){
           System.out.print(a+" ");
        }
    }



    //非递归前序遍历
    public void iteratorPre(Node node){
        Stack<Node> stack = new Stack<>();
        if(node!=null){
            stack.push(node);
            while(!stack.empty()){
                node = stack.pop();
                show(node);
                if(node.getRight()!=null){
                    stack.push(node.getRight());
                    //为什么p.getLeft() 在后，getRight()在前应为while 
                        //循环第一句就是pop visit所以要把left放上，先访问。之中方法是即压即访问法。
                }
                if(node.getLeft()!=null){
                    stack.push(node.getLeft());
                }
            }
        }
    }

    //非递归中序遍历
    public void iteratorMid(Node p){
        Stack<Node> stack = new Stack<Node>();    
        Node node = p;    
        while (node != null || stack.size() > 0) {    
            while (node != null) {    
                stack.push(node);    
                node = node.getLeft();    
            }    
            if (stack.size() > 0) {    
                node = stack.pop();    
                show(node);     
                node = node.getRight();    
            }    
        }    
    }

    //非递归后续遍历
    public void iteratorLat(Node p){
        Node q = p;    
        Stack<Node> stack = new Stack<Node>();    
        while (p != null) {    
            // 左子树入栈    
            for (; p.getLeft() != null; p = p.getLeft())    
                stack.push(p);    
            // 当前节点无右子或右子已经输出    
            while (p != null && (p.getRight() == null || p.getRight() == q)) {    
                show(p);    
                q = p;// 记录上一个已输出节点    
                if (stack.empty())    
                    return;    
                p = stack.pop();    
            }    
            // 处理右子    
            stack.push(p);    
            p = p.getRight();    
        }    
    }



    //深度
    public int dept(Node node){
        int deptleft;
        int deptright;
        if(node==null){
            return 0;
        }else {
            deptleft=dept(node.getLeft());
            deptright=dept(node.getRight());
            if(deptleft>=deptright){
              deptleft++;
              return deptleft;
            }else {
              deptright++;
              return deptright;
            }
        }
    }
}