二叉树的深度优先和广度优先遍历

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

public class DeepFirstSort {

    /**
     * 二叉树数据结构
     *
     *
     */
    public static class TreeNode {
        int data;
        TreeNode leftNode;
        TreeNode rightNode;

        public TreeNode() {

        }

        public TreeNode(int d) {
            data = d;
        }

        public TreeNode(TreeNode left, TreeNode right, int d) {
            leftNode = left;
            rightNode = right;
            data = d;
        }
    }

    public static void main(String[] args) {
        TreeNode head=new TreeNode(1);
        TreeNode second=new TreeNode(2);
        TreeNode three=new TreeNode(3);
        TreeNode four=new TreeNode(4);
        TreeNode five=new TreeNode(5);
        TreeNode six=new TreeNode(6);
        TreeNode seven=new TreeNode(7);
        head.rightNode=three;
        head.leftNode=second;
        second.rightNode=five;
        second.leftNode=four;
        three.rightNode=seven;
        three.leftNode=six;
        System.out.print("广度优先遍历结果：");
        new DeepFirstSort().BroadFirstSearch(head);
//        BroadFirstSearch(head); //BroadFirstSearch(head)必须是静态的
        System.out.println();
        System.out.print("深度优先遍历结果：");
        new DeepFirstSort().depthFirstSearch(head);
//        depthFirstSearch(head);//depthFirstSearch(head)必须是静态的
    }

    //广度优先遍历是使用队列实现的
    public  void BroadFirstSearch(TreeNode nodeHead) {
        if(nodeHead==null) {
            return;
        }
        Queue<TreeNode> myQueue=new LinkedList<>();
        myQueue.add(nodeHead);
        while(!myQueue.isEmpty()) {
            TreeNode node=myQueue.poll();//移除
            System.out.print(node.data+" ");
            if(null!=node.leftNode) {
                myQueue.add(node.leftNode);    //深度优先遍历，我们在这里采用每一行从左到右遍历
            }
            if(null!=node.rightNode) {
                myQueue.add(node.rightNode);
            }

        }
    }

    //深度优先遍历
    public void depthFirstSearch(TreeNode nodeHead) {
        if(nodeHead==null) {
            return;
        }
        Stack<TreeNode> myStack=new Stack<>();
        myStack.add(nodeHead);
        while(!myStack.isEmpty()) {
            TreeNode node=myStack.pop();    //弹出栈顶元素
            System.out.print(node.data+" ");
            if(node.rightNode!=null) {
                myStack.push(node.rightNode);    //深度优先遍历，先遍历左边，后遍历右边,栈先进后出
            }
            if(node.leftNode!=null) {
                myStack.push(node.leftNode);
            }
        }

    }

}

标签：node,优先,遍历,TreeNode,head,rightNode,二叉树,new
来源： https://blog.csdn.net/qq_41557627/article/details/114337171