Merge branch 'patch-1' of https://github.com/L-Super/hello-algo into patch-1

.gitignore

@@ -4,7 +4,9 @@
 # Editor
 .vscode/
 .idea/
+cmake-build-debug/
 hello-algo.iml
+*.dSYM/
 
 # mkdocs files
 site/

codes/c/CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.10)
+project(hello_algo C)
+
+set(CMAKE_C_STANDARD 11)
+
+include_directories(./include)
+
+add_subdirectory(include)
+add_subdirectory(chapter_computational_complexity)
+add_subdirectory(chapter_array_and_linkedlist)
+add_subdirectory(chapter_sorting)
+add_subdirectory(chapter_tree)

codes/c/chapter_array_and_linkedlist/CMakeLists.txt

@@ -0,0 +1 @@
+add_executable(array array.c)

codes/c/chapter_array_and_linkedlist/array.c

@@ -74,11 +74,11 @@ int main() {
     int size = 5;
     int arr[5];
     printf("数组 arr = ");
-    printArray(arr, size);
+    PrintArray(arr, size);
 
     int nums[5] = { 1, 3, 2, 5, 4 };
     printf("数组 nums = ");
-    printArray(nums, size);
+    PrintArray(nums, size);
     
     /* 随机访问 */
     int randomNum = randomAccess(nums, size);
@@ -89,17 +89,17 @@ int main() {
     int* res = extend(nums, size, enlarge);
     size += enlarge;
     printf("将数组长度扩展至 8 ，得到 nums = ");
-    printArray(res, size);
+    PrintArray(res, size);
     
     /* 插入元素 */
     insert(res, size, 6, 3);
     printf("在索引 3 处插入数字 6 ，得到 nums = ");
-    printArray(res, size);
+    PrintArray(res, size);
 
     /* 删除元素 */
     removeItem(res, size, 2);
     printf("删除索引 2 处的元素，得到 nums = ");
-    printArray(res, size);
+    PrintArray(res, size);
     
     /* 遍历数组 */
     traverse(res, size);

codes/c/chapter_computational_complexity/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_executable(time_complexity time_complexity.c )
+add_executable(worst_best_time_complexity worst_best_time_complexity.c)

codes/c/chapter_computational_complexity/worst_best_time_complexity.c

@@ -41,7 +41,7 @@ int main(int argc, char *argv[]) {
         int *nums = randomNumbers(n);
         int index = findOne(nums, n);
         printf("\n数组 [ 1, 2, ..., n ] 被打乱后 = ");
-        printArray(nums, n);
+        PrintArray(nums, n);
         printf("数字 1 的索引为 %d\n", index);
         // 释放堆区内存
         if (nums != NULL) {
@@ -49,6 +49,5 @@ int main(int argc, char *argv[]) {
             nums = NULL;
         }
     }
-    getchar();
     return 0;
 }

codes/c/chapter_sorting/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_executable(bubble_sort bubble_sort.c)
+add_executable(insertion_sort insertion_sort.c)

codes/c/chapter_sorting/bubble_sort.c

@@ -50,14 +50,14 @@ void bubble_sort_with_flag(int nums[], int size) {
 /* Driver Code */
 int main() {
     int nums[6] = {4, 1, 3, 1, 5, 2};
-    printf("冒泡排序后:\n");
+    printf("冒泡排序后: ");
     bubble_sort(nums, 6);
     for (int i = 0; i < 6; i++)
     {
         printf("%d ", nums[i]);
     }
 
-    printf("优化版冒泡排序后:\n");
+    printf("\n优化版冒泡排序后: ");
     bubble_sort_with_flag(nums, 6);
     for (int i = 0; i < 6; i++)
     {

codes/c/chapter_sorting/insertion_sort.c

@@ -28,7 +28,7 @@ void insertionSort(int nums[], int size) {
 int main() {
     int nums[] = {4, 1, 3, 1, 5, 2};
     insertionSort(nums, 6);
-    printf("插入排序完成后 nums = \n");
+    printf("插入排序完成后 nums = ");
     for (int i = 0; i < 6; i++)
     {
         printf("%d ", nums[i]);

codes/c/chapter_tree/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_executable(binary_search binary_tree.c)
+add_executable(binary_tree_bfs binary_tree_bfs.c)
+add_executable(binary_tree_dfs binary_tree_dfs.c)
+add_executable(binary_search_tree binary_search_tree.c)

codes/c/chapter_tree/binary_search_tree.c

@@ -0,0 +1,8 @@
+/**
+ * File: binary_search_tree.c
+ * Created Time: 2023-01-11
+ * Author: Reanon (793584285@qq.com)
+ */
+
+#include "../include/include.h"
+

codes/c/chapter_tree/binary_tree.c

@@ -0,0 +1,43 @@
+/**
+ * File: binary_tree.c
+ * Created Time: 2023-01-11
+ * Author: Reanon (793584285@qq.com)
+ */
+
+#include "../include/include.h"
+
+/* Driver Code */
+int main() {
+    /* 初始化二叉树 */
+    // 初始化结点
+    TreeNode* n1 = NewTreeNode(1);
+    TreeNode* n2 = NewTreeNode(2);
+    TreeNode* n3 = NewTreeNode(3);
+    TreeNode* n4 = NewTreeNode(4);
+    TreeNode* n5 = NewTreeNode(5);
+    // 构建引用指向（即指针）
+    n1->left = n2;
+    n1->right = n3;
+    n2->left = n4;
+    n2->right = n5;
+    printf("初始化二叉树\n");
+    PrintTree(n1);
+
+    /* 插入与删除结点 */
+    TreeNode* P = NewTreeNode(0);
+    // 在 n1 -> n2 中间插入结点 P
+    n1->left = P;
+    P->left = n2;
+    printf("插入结点 P 后\n");
+    PrintTree(n1);
+
+    // 删除结点 P
+    n1->left = n2;
+    // 释放内存
+    free(P);
+    printf("删除结点 P 后\n");
+    PrintTree(n1);
+
+    return 0;
+}
+

codes/c/chapter_tree/binary_tree_bfs.c

@@ -0,0 +1,66 @@
+/**
+ * File: binary_tree_bfs.c
+ * Created Time: 2023-01-11
+ * Author: Reanon (793584285@qq.com)
+ */
+
+#include "../include/include.h"
+
+/* 层序遍历 */
+int *levelOrder(TreeNode *root, int *size) {
+    /* 辅助队列 */
+    int front, rear;
+    int index, *arr;
+    TreeNode *node;
+    TreeNode **queue;
+
+    /* 辅助队列 */
+    queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
+    // 队列指针
+    front = 0, rear = 0;
+    // 加入根结点
+    queue[rear++] = root;
+    // 初始化一个列表，用于保存遍历序列
+    /* 辅助数组 */
+    arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
+    // 数组指针
+    index = 0;
+    while (front < rear) {
+        // 队列出队
+        node = queue[front++];
+        // 保存结点
+        arr[index++] = node->val;
+        if (node->left != NULL) {
+            // 左子结点入队
+            queue[rear++] = node->left;
+        }
+        if (node->right != NULL) {
+            // 右子结点入队
+            queue[rear++] = node->right;
+        }
+    }
+    // 更新数组长度的值
+    *size = index;
+    arr = realloc(arr, sizeof(int) * (*size));
+    return arr;
+}
+
+
+/* Driver Code */
+int main() {
+    /* 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
+    int nums[] = {1, 2, 3, NIL, 5, 6, NIL};
+    int size = sizeof(nums) / sizeof(int);
+    TreeNode *root = ArrayToTree(nums, size);
+    printf("初始化二叉树\n");
+    PrintTree(root);
+
+    /* 层序遍历 */
+    // 需要传入数组的长度
+    int *arr = levelOrder(root, &size);
+    printf("层序遍历的结点打印序列 = ");
+    PrintArray(arr, size);
+
+    return 0;
+}

codes/c/chapter_tree/binary_tree_dfs.c

@@ -0,0 +1,72 @@
+/**
+ * File: binary_tree_dfs.c
+ * Created Time: 2023-01-11
+ * Author: Reanon (793584285@qq.com)
+ */
+
+#include "../include/include.h"
+
+/* 辅助数组，用于存储遍历序列 */
+int *arr;
+
+/* 前序遍历 */
+void preOrder(TreeNode *root, int *size) {
+
+    if (root == NULL) return;
+    // 访问优先级：根结点 -> 左子树 -> 右子树
+    arr[(*size)++] = root->val;
+    preOrder(root->left, size);
+    preOrder(root->right, size);
+}
+
+/* 中序遍历 */
+void inOrder(TreeNode *root, int *size) {
+    if (root == NULL) return;
+    // 访问优先级：左子树 -> 根结点 -> 右子树
+    inOrder(root->left, size);
+    arr[(*size)++] = root->val;
+    inOrder(root->right, size);
+}
+
+/* 后序遍历 */
+void postOrder(TreeNode *root, int *size) {
+    if (root == NULL) return;
+    // 访问优先级：左子树 -> 右子树 -> 根结点
+    postOrder(root->left, size);
+    postOrder(root->right, size);
+    arr[(*size)++] = root->val;
+}
+
+
+/* Driver Code */
+int main() {
+    /* 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
+    int nums[] = {1, 2, 3, 4, 5, 6, 7};
+    int size = sizeof(nums) / sizt ceof(int);
+    TreeNode *root = ArrayToTree(nums, size);
+    printf("初始化二叉树\n");
+    PrintTree(root);
+
+    /* 前序遍历 */
+    // 初始化辅助数组
+    arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
+    size = 0;
+    preOrder(root, &size);
+    printf("前序遍历的结点打印序列 = ");
+    PrintArray(arr, size);
+
+    /* 中序遍历 */
+    size = 0;
+    inOrder(root, &size);
+    printf("中序遍历的结点打印序列 = ");
+    PrintArray(arr, size);
+
+    /* 后序遍历 */
+    size = 0;
+    postOrder(root, &size);
+    printf("后序遍历的结点打印序列 = ");
+    PrintArray(arr, size);
+
+    return 0;
+}

codes/c/include/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_executable(include
+        include_test.c
+        include.h print_util.h
+        list_node.h tree_node.h)

codes/c/include/include.h

@@ -1,13 +1,28 @@
 /**
  * File: include.h
  * Created Time: 2022-12-20
- * Author: MolDuM (moldum@163.com)
+ * Author: MolDuM (moldum@163.com)、Reanon (793584285@qq.com)
  */
 
+#ifndef C_INCLUDE_H
+#define C_INCLUDE_H
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
 #include <time.h>
 
-#include "PrintUtil.h"
+#include "list_node.h"
+#include "tree_node.h"
+#include "print_util.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_INCLUDE_H

codes/c/include/include_test.c

@@ -0,0 +1,38 @@
+/**
+ * File: include_test.c
+ * Created Time: 2023-01-10
+ * Author: Reanon (793584285@qq.com)
+ */
+
+#include "include.h"
+
+void testListNode() {
+    int nums[] = {2, 3, 5, 6, 7};
+    int size = sizeof(nums) / sizeof(int);
+    ListNode *head = ArrayToLinkedList(nums, size);
+    PrintLinkedList(head);
+
+    ListNode *node = GetListNode(head, 5);
+    printf("find node: %d\n", node->val);
+}
+
+void testTreeNode() {
+    int nums[] = {1, 2, 3, NIL, 5, 6, NIL};
+    int size = sizeof(nums) / sizeof(int);
+    TreeNode *root = ArrayToTree(nums, size);
+
+    // print tree
+    PrintTree(root);
+
+    // tree to arr
+    int *arr = TreeToArray(root);
+    PrintArray(arr, size);
+}
+
+int main(int argc, char *argv[]) {
+    printf("==testListNode==\n");
+    testListNode();
+    printf("==testTreeNode==\n");
+    testTreeNode();
+    return 0;
+}

codes/c/include/list_node.h

@@ -0,0 +1,72 @@
+/**
+ * File: list_node.h
+ * Created Time: 2023-01-09
+ * Author: Reanon (793584285@qq.com)
+ */
+#ifndef LIST_NODE_H
+#define LIST_NODE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Definition for a singly-linked list node
+ *
+ */
+struct ListNode {
+    int val;               // 结点值
+    struct ListNode *next; // 指向下一结点的指针（引用）
+};
+
+// typedef 为 C 语言的关键字，作用是为一种数据类型定义一个新名字
+typedef struct ListNode ListNode;
+
+ListNode *NewListNode(int val) {
+    ListNode *node, *next;
+    node = (ListNode *) malloc(sizeof(ListNode));
+    node->val = val;
+    node->next = NULL;
+    return node;
+}
+
+/**
+ * @brief Generate a linked list with a vector
+ *
+ * @param list
+ * @return ListNode*
+ */
+
+ListNode *ArrayToLinkedList(const int *arr, size_t size) {
+    if (size <= 0) {
+        return NULL;
+    }
+
+    ListNode *dummy = NewListNode(0);
+    ListNode *node = dummy;
+    for (int i = 0; i < size; i++) {
+        node->next = NewListNode(arr[i]);
+        node = node->next;
+    }
+    return dummy->next;
+}
+
+/**
+ * @brief Get a list node with specific value from a linked list
+ *
+ * @param head
+ * @param val
+ * @return ListNode*
+ */
+ListNode *GetListNode(ListNode *head, int val) {
+    while (head != NULL && head->val != val) {
+        head = head->next;
+    }
+    return head;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // LIST_NODE_H

codes/c/include/print_util.h

@@ -0,0 +1,135 @@
+/**
+ * File: print_util.h
+ * Created Time: 2022-12-21
+ * Author: MolDum (moldum@163.com)、Reanon (793584285@qq.com)
+ */
+
+#ifndef PRINT_UTIL_H
+#define PRINT_UTIL_H
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "list_node.h"
+#include "tree_node.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/**
+ * @brief Print an Array
+ *
+ * @param arr
+ * @param size
+ */
+static void PrintArray(int *arr, int size) {
+    printf("[");
+    for (int i = 0; i < size - 1; i++) {
+        if (arr[i] != NIL) {
+            printf("%d, ", arr[i]);
+        } else {
+            printf("NULL, ");
+        }
+    }
+    if (arr[size - 1] != NIL) {
+        printf("%d]\n", arr[size - 1]);
+    }else{
+        printf("NULL]\n");
+    }
+}
+
+/**
+ * @brief Print a linked list
+ *
+ * @param head
+ */
+static void PrintLinkedList(ListNode *node) {
+    if (node == NULL) {
+        return;
+    }
+    while (node->next != NULL) {
+        printf("%d -> ", node->val);
+        node = node->next;
+    }
+    printf("%d\n", node->val);
+}
+
+struct Trunk {
+    struct Trunk *prev;
+    char *str;
+};
+
+typedef struct Trunk Trunk;
+
+Trunk *newTrunk(Trunk *prev, char *str) {
+    Trunk *trunk = (Trunk *) malloc(sizeof(Trunk));
+    trunk->prev = prev;
+    trunk->str = (char *) malloc(sizeof(char) * 10);
+    strcpy(trunk->str, str);
+    return trunk;
+}
+
+/**
+ * @brief Helper function to print branches of the binary tree
+ *
+ * @param trunk
+ */
+void showTrunks(Trunk *trunk) {
+    if (trunk == NULL) {
+        return;
+    }
+    showTrunks(trunk->prev);
+    printf("%s", trunk->str);
+}
+
+/**
+ * Help to print a binary tree, hide more details
+ * @param node
+ * @param prev
+ * @param isLeft
+ */
+static void printTreeHelper(TreeNode *node, Trunk *prev, bool isLeft) {
+    if (node == NULL) {
+        return;
+    }
+    char *prev_str = "    ";
+    Trunk *trunk = newTrunk(prev, prev_str);
+    printTreeHelper(node->right, trunk, true);
+    if (prev == NULL) {
+        trunk->str = "———";
+    } else if (isLeft) {
+        trunk->str = "/———";
+        prev_str = "   |";
+    } else {
+        trunk->str = "\\———";
+        prev->str = prev_str;
+    }
+    showTrunks(trunk);
+    printf("%d\n", node->val);
+
+    if (prev != NULL) {
+        prev->str = prev_str;
+    }
+    trunk->str = "   |";
+
+    printTreeHelper(node->left, trunk, false);
+}
+
+/**
+ * @brief Print a binary tree
+ *
+ * @param head
+ */
+static void PrintTree(TreeNode *root) {
+    printTreeHelper(root, NULL, false);
+}
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // PRINT_UTIL_H

codes/c/include/tree_node.h

@@ -0,0 +1,131 @@
+/**
+ * File: tree_node.h
+ * Created Time: 2023-01-09
+ * Author: Reanon (793584285@qq.com)
+ */
+
+
+#ifndef TREE_NODE_H
+#define TREE_NODE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define NIL ('#')
+#define MAX_NODE_SIZE 5000
+
+struct TreeNode {
+    int val;
+    int height;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+typedef struct TreeNode TreeNode;
+
+
+TreeNode *NewTreeNode(int val) {
+    TreeNode *node;
+
+    node = (TreeNode *) malloc(sizeof(TreeNode));
+    node->val = val;
+    node->height = 0;
+    node->left = NULL;
+    node->right = NULL;
+    return node;
+}
+
+/**
+ * @brief Generate a binary tree with an array
+ *
+ * @param arr
+ * @param size
+ * @return TreeNode *
+ */
+TreeNode *ArrayToTree(const int *arr, size_t size) {
+    if (size <= 0) {
+        return NULL;
+    }
+
+    int front, rear, index;
+    TreeNode *root, *node;
+    TreeNode **queue;
+
+    /* 根结点 */
+    root = NewTreeNode(arr[0]);
+    /* 辅助队列 */
+    queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
+    // 队列指针
+    front = 0, rear = 0;
+    // 将根结点放入队尾
+    queue[rear++] = root;
+    // 记录遍历数组的索引
+    index = 0;
+    while (front < rear) {
+        // 取队列中的头结点，并让头结点出队
+        node = queue[front++];
+        index++;
+        if (index < size) {
+            if (arr[index] != NIL) {
+                node->left = NewTreeNode(arr[index]);
+                queue[rear++] = node->left;
+            }
+        }
+        index++;
+        if (index < size) {
+            if (arr[index] != NIL) {
+                node->right = NewTreeNode(arr[index]);
+                queue[rear++] = node->right;
+            }
+        }
+    }
+    return root;
+}
+
+
+/**
+ * @brief Generate a binary tree with an array
+ *
+ * @param arr
+ * @param size
+ * @return TreeNode *
+ */
+int *TreeToArray(TreeNode *root) {
+    if (root == NULL) {
+        return NULL;
+    }
+    int front, rear;
+    int index, *arr;
+    TreeNode *node;
+    TreeNode **queue;
+    /* 辅助队列 */
+    queue = (TreeNode **) malloc(sizeof(TreeNode) * MAX_NODE_SIZE);
+    // 队列指针
+    front = 0, rear = 0;
+    // 将根结点放入队尾
+    queue[rear++] = root;
+    /* 辅助数组 */
+    arr = (int *) malloc(sizeof(int) * MAX_NODE_SIZE);
+    // 数组指针
+    index = 0;
+    while (front < rear) {
+        // 取队列中的头结点，并让头结点出队
+        node = queue[front++];
+        if (node != NULL) {
+            arr[index] = node->val;
+            queue[rear++] = node->left;
+            queue[rear++] = node->right;
+        } else {
+            arr[index] = NIL;
+        }
+        index++;
+    }
+    return arr;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // TREE_NODE_H

codes/go/chapter_tree/binary_search_tree_test.go

@@ -20,7 +20,7 @@ func TestBinarySearchTree(t *testing.T) {
 	fmt.Println("\n二叉树的根结点为:", node.Val)
 
 	// 查找结点
-	node = bst.Search(7)
+	node = bst.search(7)
 	fmt.Println("查找到的结点对象为", node, "，结点值 =", node.Val)
 
 	// 插入结点

codes/swift/Package.swift

@@ -13,6 +13,9 @@ let package = Package(
         .executable(name: "linked_list", targets: ["linked_list"]),
         .executable(name: "list", targets: ["list"]),
         .executable(name: "my_list", targets: ["my_list"]),
+        .executable(name: "stack", targets: ["stack"]),
+        .executable(name: "linkedlist_stack", targets: ["linkedlist_stack"]),
+        .executable(name: "array_stack", targets: ["array_stack"]),
     ],
     targets: [
         .target(name: "utils", path: "utils"),
@@ -24,5 +27,8 @@ let package = Package(
         .executableTarget(name: "linked_list", dependencies: ["utils"], path: "chapter_array_and_linkedlist", sources: ["linked_list.swift"]),
         .executableTarget(name: "list", path: "chapter_array_and_linkedlist", sources: ["list.swift"]),
         .executableTarget(name: "my_list", path: "chapter_array_and_linkedlist", sources: ["my_list.swift"]),
+        .executableTarget(name: "stack", path: "chapter_stack_and_queue", sources: ["stack.swift"]),
+        .executableTarget(name: "linkedlist_stack", dependencies: ["utils"], path: "chapter_stack_and_queue", sources: ["linkedlist_stack.swift"]),
+        .executableTarget(name: "array_stack", path: "chapter_stack_and_queue", sources: ["array_stack.swift"]),
     ]
 )

codes/swift/chapter_stack_and_queue/array_stack.swift

@@ -0,0 +1,84 @@
+/**
+ * File: array_stack.swift
+ * Created Time: 2023-01-09
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+/* 基于数组实现的栈 */
+class ArrayStack {
+    private var stack: [Int]
+
+    init() {
+        // 初始化列表（动态数组）
+        stack = []
+    }
+
+    /* 获取栈的长度 */
+    func size() -> Int {
+        stack.count
+    }
+
+    /* 判断栈是否为空 */
+    func isEmpty() -> Bool {
+        stack.isEmpty
+    }
+
+    /* 入栈 */
+    func push(num: Int) {
+        stack.append(num)
+    }
+
+    /* 出栈 */
+    func pop() -> Int {
+        if stack.isEmpty {
+            fatalError("栈为空")
+        }
+        return stack.removeLast()
+    }
+
+    /* 访问栈顶元素 */
+    func peek() -> Int {
+        if stack.isEmpty {
+            fatalError("栈为空")
+        }
+        return stack.last!
+    }
+
+    /* 将 List 转化为 Array 并返回 */
+    func toArray() -> [Int] {
+        stack
+    }
+}
+
+@main
+enum _ArrayStack {
+    /* Driver Code */
+    static func main() {
+        /* 初始化栈 */
+        let stack = ArrayStack()
+
+        /* 元素入栈 */
+        stack.push(num: 1)
+        stack.push(num: 3)
+        stack.push(num: 2)
+        stack.push(num: 5)
+        stack.push(num: 4)
+        print("栈 stack = \(stack.toArray())")
+
+        /* 访问栈顶元素 */
+        let peek = stack.peek()
+        print("栈顶元素 peek = \(peek)")
+
+        /* 元素出栈 */
+        let pop = stack.pop()
+        print("出栈元素 pop = \(pop)，出栈后 stack = \(stack.toArray())")
+
+        /* 获取栈的长度 */
+        let size = stack.size()
+        print("栈的长度 size = \(size)")
+
+        /* 判断是否为空 */
+        let isEmpty = stack.isEmpty()
+        print("栈是否为空 = \(isEmpty)")
+    }
+}

codes/swift/chapter_stack_and_queue/linkedlist_stack.swift

@@ -0,0 +1,93 @@
+/**
+ * File: linkedlist_stack.swift
+ * Created Time: 2023-01-09
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import utils
+
+/* 基于链表实现的栈 */
+class LinkedListStack {
+    private var _peek: ListNode? // 将头结点作为栈顶
+    private var _size = 0 // 栈的长度
+
+    init() {}
+
+    /* 获取栈的长度 */
+    func size() -> Int {
+        _size
+    }
+
+    /* 判断栈是否为空 */
+    func isEmpty() -> Bool {
+        _size == 0
+    }
+
+    /* 入栈 */
+    func push(num: Int) {
+        let node = ListNode(x: num)
+        node.next = _peek
+        _peek = node
+        _size += 1
+    }
+
+    /* 出栈 */
+    func pop() -> Int {
+        let num = peek()
+        _peek = _peek?.next
+        _size -= 1
+        return num
+    }
+
+    /* 访问栈顶元素 */
+    func peek() -> Int {
+        if _size == 0 {
+            fatalError("栈为空")
+        }
+        return _peek!.val
+    }
+
+    /* 将 List 转化为 Array 并返回 */
+    func toArray() -> [Int] {
+        var node = _peek
+        var res = Array(repeating: 0, count: _size)
+        for i in sequence(first: res.count - 1, next: { $0 >= 0 + 1 ? $0 - 1 : nil }) {
+            res[i] = node!.val
+            node = node?.next
+        }
+        return res
+    }
+}
+
+@main
+enum _LinkedListStack {
+    /* Driver Code */
+    static func main() {
+        /* 初始化栈 */
+        let stack = LinkedListStack()
+
+        /* 元素入栈 */
+        stack.push(num: 1)
+        stack.push(num: 3)
+        stack.push(num: 2)
+        stack.push(num: 5)
+        stack.push(num: 4)
+        print("栈 stack = \(stack.toArray())")
+
+        /* 访问栈顶元素 */
+        let peek = stack.peek()
+        print("栈顶元素 peek = \(peek)")
+
+        /* 元素出栈 */
+        let pop = stack.pop()
+        print("出栈元素 pop = \(pop)，出栈后 stack = \(stack.toArray())")
+
+        /* 获取栈的长度 */
+        let size = stack.size()
+        print("栈的长度 size = \(size)")
+
+        /* 判断是否为空 */
+        let isEmpty = stack.isEmpty()
+        print("栈是否为空 = \(isEmpty)")
+    }
+}

codes/swift/chapter_stack_and_queue/stack.swift

@@ -0,0 +1,39 @@
+/**
+ * File: stack.swift
+ * Created Time: 2023-01-09
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+@main
+enum Stack {
+    /* Driver Code */
+    static func main() {
+        /* 初始化栈 */
+        // Swift 没有内置的栈类，可以把 Array 当作栈来使用
+        var stack: [Int] = []
+
+        /* 元素入栈 */
+        stack.append(1)
+        stack.append(3)
+        stack.append(2)
+        stack.append(5)
+        stack.append(4)
+        print("栈 stack = \(stack)")
+
+        /* 访问栈顶元素 */
+        let peek = stack.last!
+        print("栈顶元素 peek = \(peek)")
+
+        /* 元素出栈 */
+        let pop = stack.removeLast()
+        print("出栈元素 pop = \(pop)，出栈后 stack = \(stack)")
+
+        /* 获取栈的长度 */
+        let size = stack.count
+        print("栈的长度 size = \(size)")
+
+        /* 判断是否为空 */
+        let isEmpty = stack.isEmpty
+        print("栈是否为空 = \(isEmpty)")
+    }
+}

docs/chapter_computational_complexity/time_complexity.md

@@ -1434,11 +1434,14 @@ $$
         for (int i = n - 1; i > 0; i--) {
             // 内循环：冒泡操作
             for (int j = 0; j < i; j++) {
-                // 交换 nums[j] 与 nums[j + 1]
-                int tmp = nums[j];
-                nums[j] = nums[j + 1];
-                nums[j + 1] = tmp;
-                count += 3;  // 元素交换包含 3 个单元操作
+                if (nums[j] > nums [j + 1]) 
+                {
+                    // 交换 nums[j] 与 nums[j + 1]
+                    int tmp = nums[j];
+                    nums[j] = nums[j + 1];
+                    nums[j + 1] = tmp;
+                    count += 3;  // 元素交换包含 3 个单元操作
+                }
             }
             
         }

docs/chapter_stack_and_queue/stack.md

@@ -231,7 +231,28 @@ comments: true
 === "Swift"
 
     ```swift title="stack.swift"
+    /* 初始化栈 */
+    // Swift 没有内置的栈类，可以把 Array 当作栈来使用
+    var stack: [Int] = []
 
+    /* 元素入栈 */
+    stack.append(1)
+    stack.append(3)
+    stack.append(2)
+    stack.append(5)
+    stack.append(4)
+
+    /* 访问栈顶元素 */
+    let peek = stack.last!
+
+    /* 元素出栈 */
+    let pop = stack.removeLast()
+
+    /* 获取栈的长度 */
+    let size = stack.count
+
+    /* 判断是否为空 */
+    let isEmpty = stack.isEmpty
     ```
 
 ## 栈的实现
@@ -606,7 +627,58 @@ comments: true
 === "Swift"
 
     ```swift title="linkedlist_stack.swift"
+    /* 基于链表实现的栈 */
+    class LinkedListStack {
+        private var _peek: ListNode? // 将头结点作为栈顶
+        private var _size = 0 // 栈的长度
 
+        init() {}
+
+        /* 获取栈的长度 */
+        func size() -> Int {
+            _size
+        }
+
+        /* 判断栈是否为空 */
+        func isEmpty() -> Bool {
+            _size == 0
+        }
+
+        /* 入栈 */
+        func push(num: Int) {
+            let node = ListNode(x: num)
+            node.next = _peek
+            _peek = node
+            _size += 1
+        }
+
+        /* 出栈 */
+        func pop() -> Int {
+            let num = peek()
+            _peek = _peek?.next
+            _size -= 1
+            return num
+        }
+
+        /* 访问栈顶元素 */
+        func peek() -> Int {
+            if _size == 0 {
+                fatalError("栈为空")
+            }
+            return _peek!.val
+        }
+
+        /* 将 List 转化为 Array 并返回 */
+        func toArray() -> [Int] {
+            var node = _peek
+            var res = Array(repeating: 0, count: _size)
+            for i in sequence(first: res.count - 1, next: { $0 >= 0 + 1 ? $0 - 1 : nil }) {
+                res[i] = node!.val
+                node = node?.next
+            }
+            return res
+        }
+    }
     ```
 
 ### 基于数组的实现
@@ -897,7 +969,51 @@ comments: true
 === "Swift"
 
     ```swift title="array_stack.swift"
+    /* 基于数组实现的栈 */
+    class ArrayStack {
+        private var stack: [Int]
 
+        init() {
+            // 初始化列表（动态数组）
+            stack = []
+        }
+
+        /* 获取栈的长度 */
+        func size() -> Int {
+            stack.count
+        }
+
+        /* 判断栈是否为空 */
+        func isEmpty() -> Bool {
+            stack.isEmpty
+        }
+
+        /* 入栈 */
+        func push(num: Int) {
+            stack.append(num)
+        }
+
+        /* 出栈 */
+        func pop() -> Int {
+            if stack.isEmpty {
+                fatalError("栈为空")
+            }
+            return stack.removeLast()
+        }
+
+        /* 访问栈顶元素 */
+        func peek() -> Int {
+            if stack.isEmpty {
+                fatalError("栈为空")
+            }
+            return stack.last!
+        }
+
+        /* 将 List 转化为 Array 并返回 */
+        func toArray() -> [Int] {
+            stack
+        }
+    }
     ```
 
 !!! tip

docs/chapter_tree/binary_tree.md

@@ -114,7 +114,7 @@ comments: true
 
 结点的两个指针分别指向「左子结点 Left Child Node」和「右子结点 Right Child Node」，并且称该结点为两个子结点的「父结点 Parent Node」。给定二叉树某结点，将左子结点以下的树称为该结点的「左子树 Left Subtree」，右子树同理。
 
-除了叶结点外，每个结点都有子结点和子树。例如，若将上图的「结点 2」看作父结点，那么其左子结点和右子结点分别为「结点 4」和「结点 5」，左子树和右子树分别为「结点 4 以下的树」和「结点 5 以下的树」。
+除了叶结点外，每个结点都有子结点和子树。例如，若将上图的「结点 2」看作父结点，那么其左子结点和右子结点分别为「结点 4」和「结点 5」，左子树和右子树分别为「结点 4 及其以下结点形成的树」和「结点 5 及其以下结点形成的树」。
 
 ![binary_tree_definition](binary_tree.assets/binary_tree_definition.png)