Merge branch 'krahets:master' into master

codes/java/chapter_hashing/array_hash_map.java

@@ -0,0 +1,138 @@
+/*
+ * File: hash_map.java
+ * Created Time: 2022-12-04
+ * Author: Krahets (krahets@163.com)
+ */
+
+package chapter_hashing;
+import java.util.*;
+
+/* 键值对 int->String */
+class Entry {
+    public int key;
+    public String val;
+    public Entry(int key, String val) {
+        this.key = key;
+        this.val = val;
+    }
+}
+
+/* 基于数组简易实现的哈希表 */
+class ArrayHashMap {
+    private List<Entry> bucket;
+    public ArrayHashMap() {
+        // 初始化一个长度为 10 的桶（数组）
+        bucket = new ArrayList<>(10);
+        for (int i = 0; i < 10; i++) {
+            bucket.add(null);
+        }
+    }
+
+    /* 哈希函数 */
+    private int hashFunc(int key) {
+        int index = key % 10000;
+        return index;
+    }
+
+    /* 查询操作 */
+    public String get(int key) {
+        int index = hashFunc(key);
+        Entry pair = bucket.get(index);
+        if (pair == null) return null;
+        return pair.val;
+    }
+
+    /* 添加操作 */
+    public void put(int key, String val) {
+        Entry pair = new Entry(key, val);
+        int index = hashFunc(key);
+        bucket.set(index, pair);
+    }
+
+    /* 删除操作 */
+    public void remove(int key) {
+        int index = hashFunc(key);
+        // 置为空字符，代表删除
+        bucket.set(index, null);
+    }
+
+    /* 获取所有键值对 */
+    public List<Entry> entrySet() {
+        List<Entry> entrySet = new ArrayList<>();
+        for (Entry pair : bucket) {
+            if (pair != null)
+                entrySet.add(pair);
+        }
+        return entrySet;
+    }
+
+    /* 获取所有键 */
+    public List<Integer> keySet() {
+        List<Integer> keySet = new ArrayList<>();
+        for (Entry pair : bucket) {
+            if (pair != null)
+                keySet.add(pair.key);
+        }
+        return keySet;
+    }
+
+    /* 获取所有值 */
+    public List<String> valueSet() {
+        List<String> valueSet = new ArrayList<>();
+        for (Entry pair : bucket) {
+            if (pair != null)
+                valueSet.add(pair.val);
+        }
+        return valueSet;
+    }
+
+    /* 打印哈希表 */
+    public void print() {
+        for (Entry kv: entrySet()) {
+            System.out.println(kv.key + " -> " + kv.val);
+        }
+    }
+}
+
+
+public class array_hash_map {
+    public static void main(String[] args) {
+        /* 初始化哈希表 */
+        ArrayHashMap map = new ArrayHashMap();
+
+        /* 添加操作 */
+        // 在哈希表中添加键值对 (key, value)
+        map.put(10001, "小哈");   
+        map.put(10002, "小啰");   
+        map.put(10003, "小算");   
+        map.put(10004, "小法");
+        map.put(10005, "小哇");
+        System.out.println("\n添加完成后，哈希表为\nKey -> Value");
+        map.print();
+
+        /* 查询操作 */
+        // 向哈希表输入键 key ，得到值 value
+        String name = map.get(10002);
+        System.out.println("\n输入学号 10002 ，查询到姓名 " + name);
+
+        /* 删除操作 */
+        // 在哈希表中删除键值对 (key, value)
+        map.remove(10005);
+        System.out.println("\n删除 10005 后，哈希表为\nKey -> Value");
+        map.print();
+
+        /* 遍历哈希表 */
+        System.out.println("\n遍历键值对 Key->Value");
+        for (Entry kv: map.entrySet()) {
+            System.out.println(kv.key + " -> " + kv.val);
+        }
+        System.out.println("\n单独遍历键 Key");
+        for (int key: map.keySet()) {
+            System.out.println(key);
+        }
+        System.out.println("\n单独遍历值 Value");
+        for (String val: map.valueSet()) {
+            System.out.println(val);
+        }
+    }
+}

codes/java/chapter_hashing/hash_map.java

@@ -0,0 +1,51 @@
+/*
+ * File: hash_map.java
+ * Created Time: 2022-12-04
+ * Author: Krahets (krahets@163.com)
+ */
+
+package chapter_hashing;
+import java.util.*;
+import include.*;
+
+public class hash_map {
+    public static void main(String[] args) {
+        /* 初始化哈希表 */
+        Map<Integer, String> map = new HashMap<>();
+
+        /* 添加操作 */
+        // 在哈希表中添加键值对 (key, value)
+        map.put(10001, "小哈");   
+        map.put(10002, "小啰");   
+        map.put(10003, "小算");   
+        map.put(10004, "小法");
+        map.put(10005, "小哇");
+        System.out.println("\n添加完成后，哈希表为\nKey -> Value");
+        PrintUtil.printHashMap(map);
+
+        /* 查询操作 */
+        // 向哈希表输入键 key ，得到值 value
+        String name = map.get(10002);
+        System.out.println("\n输入学号 10002 ，查询到姓名 " + name);
+
+        /* 删除操作 */
+        // 在哈希表中删除键值对 (key, value)
+        map.remove(10005);
+        System.out.println("\n删除 10005 后，哈希表为\nKey -> Value");
+        PrintUtil.printHashMap(map);
+
+        /* 遍历哈希表 */
+        System.out.println("\n遍历键值对 Key->Value");
+        for (Map.Entry <Integer, String> kv: map.entrySet()) {
+            System.out.println(kv.getKey() + " -> " + kv.getValue());
+        }
+        System.out.println("\n单独遍历键 Key");
+        for (int key: map.keySet()) {
+            System.out.println(key);
+        }
+        System.out.println("\n单独遍历值 Value");
+        for (String val: map.values()) {
+            System.out.println(val);
+        }
+    }
+}

codes/java/include/PrintUtil.java

@@ -91,4 +91,16 @@ public class PrintUtil {
         showTrunks(p.prev);
         System.out.print(p.str);
     }
+
+    /**
+     * Print a hash map
+     * @param <K>
+     * @param <V>
+     * @param map
+     */
+    public static <K, V> void printHashMap(Map<K, V> map) {
+        for (Map.Entry <K, V> kv: map.entrySet()) {
+            System.out.println(kv.getKey() + " -> " + kv.getValue());
+        }
+    }
 }

codes/javascript/chapter_stack_and_queue/stack.js

@@ -0,0 +1,34 @@
+/**
+ * File: stack.js
+ * Created Time: 2022-12-04
+ * Author: S-N-O-R-L-A-X (snorlax.xu@outlook.com)
+ */
+
+/* 初始化栈 */
+// Javascript 没有内置的栈类，可以把 Array 当作栈来使用 
+const stack = [];
+
+/* 元素入栈 */
+stack.push(1);
+stack.push(3);
+stack.push(2);
+stack.push(5);
+stack.push(4);
+console.log("栈 stack =", stack)
+
+/* 访问栈顶元素 */
+const peek = stack[stack.length - 1];
+console.log("栈顶元素 peek =", peek)
+
+/* 元素出栈 */
+const pop = stack.pop();
+console.log("出栈元素 pop =", pop)
+console.log("出栈后 stack =", stack)
+
+/* 获取栈的长度 */
+const size = stack.length;
+console.log("栈的长度 size =", size)
+
+/* 判断是否为空 */
+const is_empty = stack.length === 0;
+console.log("栈是否为空 =", is_empty)

codes/javascript/chapter_tree/binary_search_tree.js

@@ -0,0 +1,146 @@
+/**
+ * File: binary_tree.js
+ * Created Time: 2022-12-04
+ * Author: IsChristina (christinaxia77@foxmail.com)
+ */
+
+const Tree = require("../include/TreeNode");
+const { printTree } = require("../include/PrintUtil");
+
+/* 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");
+printTree(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");
+printTree(getRoot());
+
+/* 删除结点 */
+remove(1);
+console.log("\n删除结点 1 后，二叉树为\n");
+printTree(getRoot());
+remove(2);
+console.log("\n删除结点 2 后，二叉树为\n");
+printTree(getRoot());
+remove(4);
+console.log("\n删除结点 4 后，二叉树为\n");
+printTree(getRoot());

codes/javascript/chapter_tree/binary_tree.js

@@ -0,0 +1,35 @@
+/**
+ * File: binary_tree.js
+ * Created Time: 2022-12-04
+ * Author: IsChristina (christinaxia77@foxmail.com)
+ */
+
+const Tree = require("../include/TreeNode");
+const { printTree } = require("../include/PrintUtil");
+
+/* 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")
+printTree(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");
+printTree(n1);
+// 删除结点 P
+n1.left = n2;
+console.log("\n删除结点 P 后\n");
+printTree(n1);

codes/javascript/chapter_tree/binary_tree_bfs.js

@@ -0,0 +1,37 @@
+/**
+ * File: binary_tree.js
+ * Created Time: 2022-12-04
+ * Author: IsChristina (christinaxia77@foxmail.com)
+ */
+
+const { arrToTree } = require("../include/TreeNode");
+const { printTree } = require("../include/PrintUtil");
+
+/* 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");
+printTree(root);
+
+/* 层序遍历 */
+let list = hierOrder(root);
+console.log("\n层序遍历的结点打印序列 = " + list);

codes/javascript/chapter_tree/binary_tree_dfs.js

@@ -0,0 +1,61 @@
+/**
+ * File: binary_tree.js
+ * Created Time: 2022-12-04
+ * Author: IsChristina (christinaxia77@foxmail.com)
+ */
+
+const { arrToTree } = require("../include/TreeNode");
+const { printTree } = require("../include/PrintUtil");
+
+// 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");
+printTree(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);
+

codes/javascript/include/PrintUtil.js

@@ -0,0 +1,88 @@
+/**
+ * File: PrintUtil.js
+ * Created Time: 2022-12-04
+ * Author: IsChristina (christinaxia77@foxmail.com)
+ */
+
+function Trunk(prev, str) {
+    this.prev = prev;
+    this.str = str;
+}
+
+/**
+ * Print a linked list
+ * @param head
+ */
+function printLinkedList(head) {
+    let list = [];
+    while (head !== null) {
+        list.push(head.val.toString());
+        head = head.next;
+    }
+    console.log(list.join(" -> "));
+}
+
+/**
+ * The interface of the tree printer
+ * This tree printer is borrowed from TECHIE DELIGHT
+ * https://www.techiedelight.com/c-program-print-binary-tree/
+ * @param root
+ */
+function printTree(root) {
+    printTree(root, null, false);
+}
+
+/**
+ * Print a binary tree
+ * @param root
+ * @param prev
+ * @param isLeft
+ */
+function printTree(root, prev, isLeft) {
+    if (root === null) {
+        return;
+    }
+
+    let prev_str = "    ";
+    let trunk = new Trunk(prev, prev_str);
+
+    printTree(root.right, trunk, true);
+
+    if (!prev) {
+        trunk.str = "———";
+    } else if (isLeft) {
+        trunk.str = "/———";
+        prev_str = "   |";
+    } else {
+        trunk.str = "\\———";
+        prev.str = prev_str;
+    }
+
+    showTrunks(trunk);
+    console.log(" " + root.val);
+
+    if (prev) {
+        prev.str = prev_str;
+    }
+    trunk.str = "   |";
+
+    printTree(root.left, trunk, false);
+}
+
+/**
+ * Helper function to print branches of the binary tree
+ * @param p
+ */
+function showTrunks(p) {
+    if (!p) {
+        return;
+    }
+
+    showTrunks(p.prev);
+    console.log(p.str);
+}
+
+module.exports = { 
+    printTree,
+    printLinkedList,
+}

codes/javascript/include/TreeNode.js

@@ -0,0 +1,47 @@
+/**
+ * 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,
+}

codes/typescript/chapter_array_and_linkedlist/array.ts

@@ -0,0 +1,101 @@
+/*
+ * File: array.ts
+ * Created Time: 2022-12-04
+ * Author: Justin (xiefahit@gmail.com)
+ */
+
+/* 随机返回一个数组元素 */
+function randomAccess(nums: number[]): number {
+    // 在区间 [0, nums.length) 中随机抽取一个数字
+    const random_index = Math.floor(Math.random() * nums.length)
+    // 获取并返回随机元素
+    const random_num = nums[random_index]
+    return random_num
+}
+
+/* 扩展数组长度 */
+// 请注意，TypeScript 的 Array 是动态数组，可以直接扩展
+// 为了方便学习，本函数将 Array 看作是长度不可变的数组
+function extend(nums: number[], enlarge: number): number[] {
+    // 初始化一个扩展长度后的数组
+    const res = new Array(nums.length + enlarge).fill(0)
+    // 将原数组中的所有元素复制到新数组
+    for (let i = 0; i < nums.length; i++){
+        res[i] = nums[i]
+    }
+    // 返回扩展后的新数组
+    return res
+}
+
+/* 在数组的索引 index 处插入元素 num */
+function insert(nums: number[], num: number, index: number): void {
+    // 把索引 index 以及之后的所有元素向后移动一位
+    for (let i = nums.length - 1; i >= index; i--) {
+        nums[i] = nums[i - 1]
+    }
+    // 将 num 赋给 index 处元素
+    nums[index] = num
+}
+
+/* 删除索引 index 处元素 */
+function remove(nums: number[], index: number): void {
+    // 把索引 index 之后的所有元素向前移动一位
+    for (let i = index; i < nums.length - 1; i++) {
+        nums[i] = nums[i + 1]
+    }
+}
+
+/* 遍历数组 */
+function traverse(nums: number[]): void {
+    let count = 0
+    // 通过索引遍历数组
+    for (let i = 0; i < nums.length; i++) {
+        count++
+    }
+    // 直接遍历数组
+    for(let num of nums){
+        count += 1
+    }
+}
+
+/* 在数组中查找指定元素 */
+function find(nums: number[], target: number): number {
+    for (let i = 0; i < nums.length; i++) {
+        if (nums[i] === target) {
+            return i
+        }
+    }
+    return -1
+}
+
+/* Driver Codes*/
+/* 初始化数组 */
+let arr: number[] = new Array(5).fill(0)
+console.log("数组 arr =", arr)
+let nums: number[] = [1, 3, 2, 5, 4]
+console.log("数组 nums =", nums)
+
+/* 随机访问 */
+const random_num = randomAccess(nums)
+console.log("在 nums 中获取随机元素", random_num)
+
+/* 长度扩展 */
+nums = extend(nums, 3)
+console.log("将数组长度扩展至 8 ，得到 nums =", nums)
+
+/* 插入元素 */
+insert(nums, 6, 3)
+console.log("在索引 3 处插入数字 6 ，得到 nums =", nums)
+
+/* 删除元素 */
+remove(nums, 2)
+console.log("删除索引 2 处的元素，得到 nums =", nums)
+
+/* 遍历数组 */
+traverse(nums)
+
+/* 查找元素 */
+var index: number = find(nums, 3)
+console.log("在 nums 中查找元素 3 ，得到索引 =", index)
+
+export { }

codes/typescript/chapter_stack_and_queue/stack.ts

@@ -0,0 +1,30 @@
+/**
+ * File: stack.ts
+ * Created Time: 2022-12-04
+ * Author: S-N-O-R-L-A-X (snorlax.xu@outlook.com)
+ */
+
+/* 初始化栈 */
+// Typescript 没有内置的栈类，可以把 Array 当作栈来使用 
+const stack: number[] = [];
+
+/* 元素入栈 */
+stack.push(1);
+stack.push(3);
+stack.push(2);
+stack.push(5);
+stack.push(4);
+
+/* 访问栈顶元素 */
+const peek = stack[stack.length - 1];
+
+/* 元素出栈 */
+const pop = stack.pop();
+
+/* 获取栈的长度 */
+const size = stack.length;
+
+/* 判断是否为空 */
+const is_empty = stack.length === 0;
+
+export { };