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add JavaScript codes for Tree

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IsChristina 2 years ago
parent ebf9024136
commit db416cf4bb
7 changed files with 462 additions and 5 deletions
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145
codes/javascript/chapter_tree/binary_search_tree.js
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/**
* File: binary_tree.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
const Tree = require("../include/TreeNode");
/* 二叉搜索树 */
var root;
function BinarySearchTree(nums) {
nums.sort((a,b) => { return a-b }); // 排序数组
root = buildTree(nums, 0, nums.length - 1); // 构建二叉搜索树
}
/* 获取二叉树根结点 */
function getRoot() {
return root;
}
/* 构建二叉搜索树 */
function buildTree(nums, i, j) {
if (i > j) return null;
// 将数组中间结点作为根结点
let mid = Math.floor((i + j) / 2);
let root = new Tree.TreeNode(nums[mid]);
// 递归建立左子树和右子树
root.left = buildTree(nums, i, mid - 1);
root.right = buildTree(nums, mid + 1, j);
return root;
}
/* 查找结点 */
function search(num) {
let cur = root;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 目标结点在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 目标结点在 root 的左子树中
else if (cur.val > num) cur = cur.left;
// 找到目标结点，跳出循环
else break;
}
// 返回目标结点
return cur;
}
/* 插入结点 */
function insert(num) {
// 若树为空，直接提前返回
if (root === null) return null;
let cur = root, pre = null;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 找到重复结点，直接返回
if (cur.val === num) return null;
pre = cur;
// 插入位置在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 插入位置在 root 的左子树中
else cur = cur.left;
}
// 插入结点 val
let node = new Tree.TreeNode(num);
if (pre.val < num) pre.right = node;
else pre.left = node;
return node;
}
/* 删除结点 */
function remove(num) {
// 若树为空，直接提前返回
if (root === null) return null;
let cur = root, pre = null;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 找到待删除结点，跳出循环
if (cur.val === num) break;
pre = cur;
// 待删除结点在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 待删除结点在 root 的左子树中
else cur = cur.left;
}
// 若无待删除结点，则直接返回
if (cur === null) return null;
// 子结点数量 = 0 or 1
if (cur.left === null || cur.right === null) {
// 当子结点数量 = 0 / 1 时， child = null / 该子结点
let child = cur.left !== null ? cur.left : cur.right;
// 删除结点 cur
if (pre.left === cur) pre.left = child;
else pre.right = child;
}
// 子结点数量 = 2
else {
// 获取中序遍历中 cur 的下一个结点
let nex = min(cur.right);
let tmp = nex.val;
// 递归删除结点 nex
remove(nex.val);
// 将 nex 的值复制给 cur
cur.val = tmp;
}
return cur;
}
/* 获取最小结点 */
function min(root) {
if (root === null) return root;
// 循环访问左子结点，直到叶结点时为最小结点，跳出
while (root.left !== null) {
root = root.left;
}
return root;
}
/* Driver Code */
/* 初始化二叉搜索树 */
var nums = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ];
BinarySearchTree(nums)
console.log("\n初始化的二叉树为\n");
console.log(getRoot());
/* 查找结点 */
let node = search(5);
console.log("\n查找到的结点对象为 " + node + "，结点值 = " + node.val);
/* 插入结点 */
node = insert(16);
console.log("\n插入结点 16 后，二叉树为\n");
console.log(getRoot());
/* 删除结点 */
remove(1);
console.log("\n删除结点 1 后，二叉树为\n");
console.log(getRoot());
remove(2);
console.log("\n删除结点 2 后，二叉树为\n");
console.log(getRoot());
remove(4);
console.log("\n删除结点 4 后，二叉树为\n");
console.log(getRoot());

34
codes/javascript/chapter_tree/binary_tree.js
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/**
* File: binary_tree.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
const Tree = require("../include/TreeNode");
/* 初始化二叉树 */
// 初始化结点
let n1 = new Tree.TreeNode(1),
n2 = new Tree.TreeNode(2),
n3 = new Tree.TreeNode(3),
n4 = new Tree.TreeNode(4),
n5 = new Tree.TreeNode(5);
// 构建引用指向（即指针）
n1.left = n2;
n1.right = n3;
n2.left = n4;
n2.right = n5;
console.log("\n初始化二叉树\n")
console.log(n1)
/* 插入与删除结点 */
let P = new Tree.TreeNode(0);
// 在 n1 -> n2 中间插入结点 P
n1.left = P;
P.left = n2;
console.log("\n插入结点 P 后\n");
console.log(n1);
// 删除结点 P
n1.left = n2;
console.log("\n删除结点 P 后\n");
console.log(n1);

36
codes/javascript/chapter_tree/binary_tree_bfs.js
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/**
* File: binary_tree.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
let { arrToTree } = require("../include/TreeNode");
/* 层序遍历 */
function hierOrder(root) {
// 初始化队列，加入根结点
let queue = [root];
// 初始化一个列表，用于保存遍历序列
let list = [];
while (queue.length) {
let node = queue.shift(); // 队列出队
list.push(node.val); // 保存结点
if (node.left)
queue.push(node.left); // 左子结点入队
if (node.right)
queue.push(node.right); // 右子结点入队
}
return list;
}
/* Driver Code */
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
var root = arrToTree([1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null ]);
console.log("\n初始化二叉树\n");
console.log(root);
/* 层序遍历 */
let list = hierOrder(root);
console.log("\n层序遍历的结点打印序列 = " + list);

60
codes/javascript/chapter_tree/binary_tree_dfs.js
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/**
* File: binary_tree.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
let { arrToTree } = require("../include/TreeNode");
// 初始化列表，用于存储遍历序列
var list = []
/* 前序遍历 */
function preOrder(root){
if (root === null) return;
// 访问优先级：根结点 -> 左子树 -> 右子树
list.push(root.val);
preOrder(root.left);
preOrder(root.right);
}
/* 中序遍历 */
function inOrder(root) {
if (root === null) return;
// 访问优先级：左子树 -> 根结点 -> 右子树
inOrder(root.left);
list.push(root.val);
inOrder(root.right);
}
/* 后序遍历 */
function postOrder(root) {
if (root === null) return;
// 访问优先级：左子树 -> 右子树 -> 根结点
postOrder(root.left);
postOrder(root.right);
list.push(root.val);
}
/* Driver Code */
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
var root = arrToTree([1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null]);
console.log("\n初始化二叉树\n");
console.log(root);
/* 前序遍历 */
list.length = 0;
preOrder(root);
console.log("\n前序遍历的结点打印序列 = " + list);
/* 中序遍历 */
list.length = 0;
inOrder(root);
console.log("\n中序遍历的结点打印序列 = " + list);
/* 后序遍历 */
list.length = 0;
postOrder(root);
console.log("\n后序遍历的结点打印序列 = " + list);

47
codes/javascript/include/TreeNode.js
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/**
* File: TreeNode.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/**
* Definition for a binary tree node.
*/
function TreeNode(val, left, right) {
this.val = (val === undefined ? 0 : val) // 结点值
this.left = (left === undefined ? null : left) // 左子结点指针
this.right = (right === undefined ? null : right) // 右子结点指针
}
/**
* Generate a binary tree with an array
* @param arr
* @return
*/
function arrToTree(arr) {
if (arr.length === 0)
return null;
let root = new TreeNode(arr[0]);
let queue = [root]
let i = 1;
while(queue.length) {
let node = queue.shift();
if(arr[i] !== null) {
node.left = new TreeNode(arr[i]);
queue.push(node.left);
}
i++;
if(arr[i] !== null) {
node.right = new TreeNode(arr[i]);
queue.push(node.right);
}
i++;
}
return root;
}
module.exports = {
TreeNode,
arrToTree,
}

76
docs/chapter_tree/binary_search_tree.md
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@ -112,7 +112,21 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_search_tree.js" ```js title="binary_search_tree.js"
/* 查找结点 */
function search(num) {
let cur = root;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 目标结点在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 目标结点在 root 的左子树中
else if (cur.val > num) cur = cur.left;
// 找到目标结点，跳出循环
else break;
}
// 返回目标结点
return cur;
}
``` ```
=== "TypeScript" === "TypeScript"
@ -240,7 +254,27 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_search_tree.js" ```js title="binary_search_tree.js"
/* 插入结点 */
function insert(num) {
// 若树为空，直接提前返回
if (root === null) return null;
let cur = root, pre = null;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 找到重复结点，直接返回
if (cur.val === num) return null;
pre = cur;
// 插入位置在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 插入位置在 root 的左子树中
else cur = cur.left;
}
// 插入结点 val
let node = new Tree.TreeNode(num);
if (pre.val < num) pre.right = node;
else pre.left = node;
return node;
}
``` ```
=== "TypeScript" === "TypeScript"
@ -471,7 +505,43 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_search_tree.js" ```js title="binary_search_tree.js"
/* 删除结点 */
function remove(num) {
// 若树为空，直接提前返回
if (root === null) return null;
let cur = root, pre = null;
// 循环查找，越过叶结点后跳出
while (cur !== null) {
// 找到待删除结点，跳出循环
if (cur.val === num) break;
pre = cur;
// 待删除结点在 root 的右子树中
if (cur.val < num) cur = cur.right;
// 待删除结点在 root 的左子树中
else cur = cur.left;
}
// 若无待删除结点，则直接返回
if (cur === null) return null;
// 子结点数量 = 0 or 1
if (cur.left === null || cur.right === null) {
// 当子结点数量 = 0 / 1 时， child = null / 该子结点
let child = cur.left !== null ? cur.left : cur.right;
// 删除结点 cur
if (pre.left === cur) pre.left = child;
else pre.right = child;
}
// 子结点数量 = 2
else {
// 获取中序遍历中 cur 的下一个结点
let nex = min(cur.right);
let tmp = nex.val;
// 递归删除结点 nex
remove(nex.val);
// 将 nex 的值复制给 cur
cur.val = tmp;
}
return cur;
}
``` ```
=== "TypeScript" === "TypeScript"

67
docs/chapter_tree/binary_tree.md
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@ -63,6 +63,12 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="" ```js title=""
/* 链表结点类 */
function TreeNode(val, left, right) {
this.val = (val === undefined ? 0 : val) // 结点值
this.left = (left === undefined ? null : left) // 左子结点指针
this.right = (right === undefined ? null : right) // 右子结点指针
}
``` ```
@ -193,7 +199,18 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_tree.js" ```js title="binary_tree.js"
/* 初始化二叉树 */
// 初始化结点
let n1 = new TreeNode(1),
n2 = new TreeNode(2),
n3 = new TreeNode(3),
n4 = new TreeNode(4),
n5 = new TreeNode(5);
// 构建引用指向（即指针）
n1.left = n2;
n1.right = n3;
n2.left = n4;
n2.right = n5;
``` ```
=== "TypeScript" === "TypeScript"
@ -265,7 +282,14 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_tree.js" ```js title="binary_tree.js"
/* 插入与删除结点 */
let P = new TreeNode(0);
// 在 n1 -> n2 中间插入结点 P
n1.left = P;
P.left = n2;
// 删除结点 P
n1.left = n2;
``` ```
=== "TypeScript" === "TypeScript"
@ -387,7 +411,23 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_tree_bfs.js" ```js title="binary_tree_bfs.js"
/* 层序遍历 */
function hierOrder(root) {
// 初始化队列，加入根结点
let queue = [root];
// 初始化一个列表，用于保存遍历序列
let list = [];
while (queue.length) {
let node = queue.shift(); // 队列出队
list.push(node.val); // 保存结点
if (node.left)
queue.push(node.left); // 左子结点入队
if (node.right)
queue.push(node.right); // 右子结点入队
}
return list;
}
``` ```
=== "TypeScript" === "TypeScript"
@ -536,7 +576,32 @@ comments: true
=== "JavaScript" === "JavaScript"
```js title="binary_tree_dfs.js" ```js title="binary_tree_dfs.js"
/* 前序遍历 */
function preOrder(root){
if (root === null) return;
// 访问优先级：根结点 -> 左子树 -> 右子树
list.push(root.val);
preOrder(root.left);
preOrder(root.right);
}
/* 中序遍历 */
function inOrder(root) {
if (root === null) return;
// 访问优先级：左子树 -> 根结点 -> 右子树
inOrder(root.left);
list.push(root.val);
inOrder(root.right);
}
/* 后序遍历 */
function postOrder(root) {
if (root === null) return;
// 访问优先级：左子树 -> 右子树 -> 根结点
postOrder(root.left);
postOrder(root.right);
list.push(root.val);
}
``` ```
=== "TypeScript" === "TypeScript"

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