LeetCode 二叉树测试用例生成器 All In One
LeetCode 二叉树测试用例生成器 All In One
二叉树生成器 / Binary Tree Generator
实现原理
递归依次遍历数组从左到右（左=>右），遇到null返回 (✅ null 后面不能有子节点了)
"use strict";
/**
*
* @author xgqfrms
* @license MIT
* @copyright xgqfrms
* @created 2023-01-01
* @modified
*
* @description LeetCode 二叉树测试用例生成器
* @difficulty Easy
* @ime_complexity O(n)
* @space_complexity O(n)
* @augments
* @example
* @link
* @solutions
*
* @best_solutions
*
*/
export {};
const log = console.log;
class TreeNode {
val: number;
left: TreeNode | null;
right: TreeNode | null;
constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
this.val = (val === undefined ? 0 : val);
this.left = (left === undefined ? null : left);
this.right = (right === undefined ? null : right);
}
}
// LeetCode tree testcase generator
// 二叉树生成原理：递归依次遍历（左=>右），遇到 null 返回 (✅ null 后面不能有子节点了)
const BinaryTreeGenerator = (arr = [], i = 0): (TreeNode | null) => {
// (arr.length - 1)下标越界 或 null 返回 null
if(i >= arr.length || arr[i] === null) {
return null;
}
const node = new TreeNode(arr[i]);
// 先左后右， 依次遍历
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
js 测试 ✅
class TreeNode {
constructor(val, left, right) {
this.val = (val === undefined ? 0 : val);
this.left = (left === undefined ? null : left);
this.right = (right === undefined ? null : right);
}
}
const BinaryTreeGenerator = (arr = [], i = 0) => {
if(i > arr.length || arr[i] === null) {
return null;
}
const node = new TreeNode(arr[i]);
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
const bt = BinaryTreeGenerator([3,9,20,null,null,15,7]);
/*
{
"val": 3,
"left": {
"val": 9,
"left": null,
"right": null
},
"right": {
"val": 20,
"left": {
"val": 15,
"left": null,
"right": null
},
"right": {
"val": 7,
"left": null,
"right": null
}
}
}
*/
https://leetcode.com/problems/maximum-depth-of-binary-tree/
bug ???
const log = console.log;
class TreeNode {
constructor(val, left, right) {
this.val = (val === undefined ? 0 : val);
this.left = (left === undefined ? null : left);
this.right = (right === undefined ? null : right);
}
}
const BinaryTreeGenerator = (arr = [], i = 0) => {
if(arr.length === 0 || i > arr.length || arr[i] === null) {
return null;
}
const node = new TreeNode(arr[i]);
// 先左后右， 依次遍历
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
BinaryTreeGenerator([1,2,2,3,4,4,3]);
const tree = BinaryTreeGenerator([1,2,2,3,4,4,3]);
// log(`tree`, tree);
log(`tree =`, JSON.stringify(tree, null, 4));
const json = {
"val": 1,
"left": {
"val": 2,
"left": {
"val": 3,
// bug ❌
"left": {
"val": 0,
"left": null,
"right": null
},
"right": null
},
"right": {
"val": 4,
"left": null,
"right": null
}
},
"right": {
"val": 2,
"left": {
"val": 4,
"left": null,
"right": null
},
"right": {
"val": 3,
"left": null,
"right": null
}
}
};
bug fix
// arr[i] === undefined ✅
const BinaryTreeGenerator = (arr: any[] = [], i: number = 0): (TreeNode | null) => {
if(arr.length === 0 || i > arr.length || arr[i] === null || arr[i] === undefined) {
return null;
}
const node = new TreeNode(arr[i]);
// 先左后右， 依次遍历
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
或者
// i >= arr.length ✅
const BinaryTreeGenerator = (arr: any[] = [], i: number = 0): (TreeNode | null) => {
if(arr.length === 0 || i >= arr.length || arr[i] === null) {
return null;
}
const node = new TreeNode(arr[i]);
// 先左后右， 依次遍历
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
https://leetcode.com/problems/symmetric-tree/
数据可视化
二叉树动态生成器动效
二叉树动态生成器组件
LeetCode 二叉树生成器是
纯函数
- 测试用例输入数据源相同：
[3,9,20,null,null,15,7] - 输出的二叉树结构也一样，具有一致性/
幂等性
纯函数
-
如果函数的调用
参数相同，则永远返回结果相同; 它不依赖于程序执行期间函数外部任何状态或数据的变化，只依赖于其输入参数。 -
该函数
不会产生任何可观察的副作用，例如网络请求，输入和输出设备或数据突变（mutation）。
幂等函数或幂等方法是指可以使用相同参数重复执行，并能获得相同结果的函数。
https://leetcode.com/problems/maximum-depth-of-binary-tree/ ✅
https://leetcode.com/problems/symmetric-tree/ ✅
...
D3.js=>SVG/ Canvas
demos
"use strict";
/**
*
* @author xgqfrms
* @license MIT
* @copyright xgqfrms
* @created 2023-01-29
* @modified 2023-02-05
*
* @description 104. 二叉树的最大深度
* @description 104. Maximum Depth of Binary Tree
* @difficulty Easy
* @ime_complexity O(n)
* @space_complexity O(n)
* @augments
* @example
* @link https://leetcode.com/problems/maximum-depth-of-binary-tree/
* @link https://leetcode.cn/problems/maximum-depth-of-binary-tree/
* @solutions
*
* @best_solutions
*
*/
// export {};
const log = console.log;
class TreeNode {
val: number;
left: TreeNode | null;
right: TreeNode | null;
constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
this.val = (val === undefined ? 0 : val);
this.left = (left === undefined ? null : left);
this.right = (right === undefined ? null : right);
}
}
function maxDepth(root: TreeNode | null): number {
if(root === null) {
return 0;
}
const arr: number[] = [];
function dfs (node, init = 0) {
let deep = init;
deep += 1;
if(node.left === null && node.right === null) {
// leaf node
arr.push(deep);
return;
}
if(node.left !== null) {
dfs(node.left, deep);
}
if(node.right !== null) {
dfs(node.right, deep);
}
}
dfs(root);
return Math.max(...arr);
};
// LeetCode tree test case
// 二叉树生成原理：递归依次遍历（左=>右），遇到 null 返回 (✅ null 后面不能有子节点了)
const BinaryTreeGenerator = (arr = [], i = 0): (TreeNode | null) => {
if(arr.length === 0 || i > arr.length || arr[i] === null) {
return null;
}
const node = new TreeNode(arr[i]);
// 先左后右， 依次遍历
node.left = BinaryTreeGenerator(arr, 2 * i + 1);
node.right = BinaryTreeGenerator(arr, 2 * i + 2);
return node ;
}
// 测试用例 test cases
const testCases = [
{
input: [3,9,20,null,null,15,7],
result: 3,
desc: 'value equal to 3',
img: 'https://assets.leetcode.com/uploads/2020/11/26/tmp-tree.jpg',
},
{
input: [1,null,2],
result: 2,
desc: 'value equal to 2',
},
{
input: [],
result: 0,
desc: 'value equal to 0',
},
];
/*
const testCase: {
input: (number | null)[];
result: number;
desc: string;
img: string;
} | {
input: (number | null)[];
result: number;
desc: string;
img?: undefined;
}
*/
for (const [i, testCase] of testCases.entries()) {
const tree = BinaryTreeGenerator(testCase.input as []);
const result = maxDepth(tree);
log(`test case ${i} result: `, result === testCase.result ? `✅ passed` : `❌ failed`, result);
}
/*
$ npx ts-node ./104\ maximum-depth-of-binary-tree.ts
*/
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refs
ChatGPT
LeetCode 二叉树生成器 / Binary Tree Generator
https://chat.openai.com/chat/330a8d3e-e74c-471f-9ed9-cac30f0a2ab9
class TreeNode {
constructor(val) {
this.val = val;
this.left = this.right = null;
}
}
function createBinaryTree(arr, i = 0) {
if (i >= arr.length || arr[i] === null) return null;
let node = new TreeNode(arr[i]);
node.left = createBinaryTree(arr, 2 * i + 1);
node.right = createBinaryTree(arr, 2 * i + 2);
return node;
}
https://www.cnblogs.com/xgqfrms/tag/ChatGPT/
https://www.cnblogs.com/xgqfrms/p/17081303.html#5146399
https://www.cnblogs.com/xgqfrms/p/17080136.html
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本文首发于博客园，作者：xgqfrms，原文链接：https://www.cnblogs.com/xgqfrms/p/17093650.html
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