package com.leetcode102;
import java.util.List;
public class Main {
public static void main(String[] args) {
Integer[] arr = {3, 9, 20, null, null, 15, 7};
TreeNode tree = createTree(arr, 0);
printPreOrder(tree);
System.out.println();
printMidOrder(tree);
System.out.println();
printAfterOrder(tree);
System.out.println();
}
/**
* 前序遍历
*/
public static void printPreOrder(TreeNode tree) {
if (tree != null) {
System.out.print(tree.val == null ? "" : tree.val + " ");
printPreOrder(tree.left);
printPreOrder(tree.right);
}
}
/**
* 中序遍历
*/
public static void printMidOrder(TreeNode tree) {
if (tree != null) {
printMidOrder(tree.left);
System.out.print(tree.val == null ? "" : tree.val + " ");
printMidOrder(tree.right);
}
}
/**
* 后序遍历
*/
public static void printAfterOrder(TreeNode tree) {
if (tree != null) {
printAfterOrder(tree.left);
printAfterOrder(tree.right);
System.out.print(tree.val == null ? "" : tree.val + " ");
}
}
/**
* 创建一个二叉树
* ----3
* -9 20
* -----15 17
*/
public static TreeNode createTree(Integer[] arr, int index) {
TreeNode root = null;
if (index < arr.length) {
root = new TreeNode(arr[index]);
root.left = createTree(arr, 2 * index + 1);
root.right = createTree(arr, 2 * index + 2);
}
return root;
}
}
class TreeNode {
Integer val;
TreeNode left;
TreeNode right;
TreeNode() {
}
TreeNode(Integer val) {
this.val = val;
}
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
leetcode二叉树相关模板
Pastthewind2023-10-27 8:43
相关推荐
倔强的小石头_3 小时前
【C语言指南】函数指针深度解析Yasin Chen3 小时前
C# Dictionary源码分析_Coin_-4 小时前
算法训练营DAY27 第八章 贪心算法 part01kangkang-6 小时前
PC端基于SpringBoot架构控制无人机(三):系统架构设计界面开发小八哥8 小时前
「Java EE开发指南」如何用MyEclipse创建一个WEB项目?(三)董董灿是个攻城狮8 小时前
5分钟搞懂什么是窗口注意力?Dann Hiroaki8 小时前
笔记分享: 哈尔滨工业大学CS31002编译原理——02. 语法分析idolyXyz8 小时前
[java: Cleaner]-一文述之一碗谦谦粉9 小时前
Maven 依赖调解的两大原则netyeaxi9 小时前
Java:使用spring-boot + mybatis如何打印SQL日志?