Add the initial EN translation for C++ code (#1346)

en/codes/cpp/chapter_array_and_linkedlist/CMakeLists.txt

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+add_executable(array array.cpp)
+add_executable(linked_list linked_list.cpp)
+add_executable(list list.cpp)
+add_executable(my_list my_list.cpp)

en/codes/cpp/chapter_array_and_linkedlist/array.cpp

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+/**
+ * File: array.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Random access to elements */
+int randomAccess(int *nums, int size) {
+    // Randomly select a number in the range [0, size)
+    int randomIndex = rand() % size;
+    // Retrieve and return a random element
+    int randomNum = nums[randomIndex];
+    return randomNum;
+}
+
+/* Extend array length */
+int *extend(int *nums, int size, int enlarge) {
+    // Initialize an extended length array
+    int *res = new int[size + enlarge];
+    // Copy all elements from the original array to the new array
+    for (int i = 0; i < size; i++) {
+        res[i] = nums[i];
+    }
+    // Free memory
+    delete[] nums;
+    // Return the new array after expansion
+    return res;
+}
+
+/* Insert element num at `index` */
+void insert(int *nums, int size, int num, int index) {
+    // Move all elements after `index` one position backward
+    for (int i = size - 1; i > index; i--) {
+        nums[i] = nums[i - 1];
+    }
+    // Assign num to the element at index
+    nums[index] = num;
+}
+
+/* Remove the element at `index` */
+void remove(int *nums, int size, int index) {
+    // Move all elements after `index` one position forward
+    for (int i = index; i < size - 1; i++) {
+        nums[i] = nums[i + 1];
+    }
+}
+
+/* Traverse array */
+void traverse(int *nums, int size) {
+    int count = 0;
+    // Traverse array by index
+    for (int i = 0; i < size; i++) {
+        count += nums[i];
+    }
+}
+
+/* Search for a specified element in the array */
+int find(int *nums, int size, int target) {
+    for (int i = 0; i < size; i++) {
+        if (nums[i] == target)
+            return i;
+    }
+    return -1;
+}
+
+/* Driver Code */
+int main() {
+    /* Initialize an array */
+    int size = 5;
+    int *arr = new int[size];
+    cout << "Array arr = ";
+    printArray(arr, size);
+
+    int *nums = new int[size]{1, 3, 2, 5, 4};
+    cout << "Array nums = ";
+    printArray(nums, size);
+
+    /* Random access */
+    int randomNum = randomAccess(nums, size);
+    cout << "Get a random element from nums = " << randomNum << endl;
+
+    /* Length extension */
+    int enlarge = 3;
+    nums = extend(nums, size, enlarge);
+    size += enlarge;
+    cout << "Extend the array length to 8, resulting in nums = ";
+    printArray(nums, size);
+
+    /* Insert element */
+    insert(nums, size, 6, 3);
+    cout << "Insert the number 6 at index 3, resulting in nums = ";
+    printArray(nums, size);
+
+    /* Remove element */
+    remove(nums, size, 2);
+    cout << "Remove the element at index 2, resulting in nums = ";
+    printArray(nums, size);
+
+    /* Traverse array */
+    traverse(nums, size);
+
+    /* Search for elements */
+    int index = find(nums, size, 3);
+    cout << "Find element 3 in nums, index = " << index << endl;
+
+    // Free memory
+    delete[] arr;
+    delete[] nums;
+
+    return 0;
+}

en/codes/cpp/chapter_array_and_linkedlist/linked_list.cpp

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+/**
+ * File: linked_list.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Insert node P after node n0 in the linked list */
+void insert(ListNode *n0, ListNode *P) {
+    ListNode *n1 = n0->next;
+    P->next = n1;
+    n0->next = P;
+}
+
+/* Remove the first node after node n0 in the linked list */
+void remove(ListNode *n0) {
+    if (n0->next == nullptr)
+        return;
+    // n0 -> P -> n1
+    ListNode *P = n0->next;
+    ListNode *n1 = P->next;
+    n0->next = n1;
+    // Free memory
+    delete P;
+}
+
+/* Access the node at `index` in the linked list */
+ListNode *access(ListNode *head, int index) {
+    for (int i = 0; i < index; i++) {
+        if (head == nullptr)
+            return nullptr;
+        head = head->next;
+    }
+    return head;
+}
+
+/* Search for the first node with value target in the linked list */
+int find(ListNode *head, int target) {
+    int index = 0;
+    while (head != nullptr) {
+        if (head->val == target)
+            return index;
+        head = head->next;
+        index++;
+    }
+    return -1;
+}
+
+/* Driver Code */
+int main() {
+    /* Initialize linked list */
+    // Initialize each node
+    ListNode *n0 = new ListNode(1);
+    ListNode *n1 = new ListNode(3);
+    ListNode *n2 = new ListNode(2);
+    ListNode *n3 = new ListNode(5);
+    ListNode *n4 = new ListNode(4);
+    // Build references between nodes
+    n0->next = n1;
+    n1->next = n2;
+    n2->next = n3;
+    n3->next = n4;
+    cout << "The initialized linked list is" << endl;
+    printLinkedList(n0);
+
+    /* Insert node */
+    insert(n0, new ListNode(0));
+    cout << "Linked list after inserting the node is" << endl;
+    printLinkedList(n0);
+
+    /* Remove node */
+    remove(n0);
+    cout << "Linked list after removing the node is" << endl;
+    printLinkedList(n0);
+
+    /* Access node */
+    ListNode *node = access(n0, 3);
+    cout << "The value of the node at index 3 in the linked list = " << node->val << endl;
+
+    /* Search node */
+    int index = find(n0, 2);
+    cout << "The index of the node with value 2 in the linked list = " << index << endl;
+
+    // Free memory
+    freeMemoryLinkedList(n0);
+
+    return 0;
+}

en/codes/cpp/chapter_array_and_linkedlist/list.cpp

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+/**
+ * File: list.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Driver Code */
+int main() {
+    /* Initialize list */
+    vector<int> nums = {1, 3, 2, 5, 4};
+    cout << "List nums = ";
+    printVector(nums);
+
+    /* Access element */
+    int num = nums[1];
+    cout << "Access the element at index 1, obtained num = " << num << endl;
+
+    /* Update element */
+    nums[1] = 0;
+    cout << "Update the element at index 1 to 0, resulting in nums = ";
+    printVector(nums);
+
+    /* Clear list */
+    nums.clear();
+    cout << "After clearing the list, nums = ";
+    printVector(nums);
+
+    /* Add element at the end */
+    nums.push_back(1);
+    nums.push_back(3);
+    nums.push_back(2);
+    nums.push_back(5);
+    nums.push_back(4);
+    cout << "After adding elements, nums = ";
+    printVector(nums);
+
+    /* Insert element in the middle */
+    nums.insert(nums.begin() + 3, 6);
+    cout << "Insert the number 6 at index 3, resulting in nums = ";
+    printVector(nums);
+
+    /* Remove element */
+    nums.erase(nums.begin() + 3);
+    cout << "Remove the element at index 3, resulting in nums = ";
+    printVector(nums);
+
+    /* Traverse the list by index */
+    int count = 0;
+    for (int i = 0; i < nums.size(); i++) {
+        count += nums[i];
+    }
+    /* Traverse the list elements */
+    count = 0;
+    for (int x : nums) {
+        count += x;
+    }
+
+    /* Concatenate two lists */
+    vector<int> nums1 = {6, 8, 7, 10, 9};
+    nums.insert(nums.end(), nums1.begin(), nums1.end());
+    cout << "Concatenate list nums1 to nums, resulting in nums = ";
+    printVector(nums);
+
+    /* Sort list */
+    sort(nums.begin(), nums.end());
+    cout << "After sorting the list, nums = ";
+    printVector(nums);
+
+    return 0;
+}

en/codes/cpp/chapter_array_and_linkedlist/my_list.cpp

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+/**
+ * File: my_list.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* List class */
+class MyList {
+  private:
+    int *arr;             // Array (stores list elements)
+    int arrCapacity = 10; // List capacity
+    int arrSize = 0;      // List length (current number of elements)
+    int extendRatio = 2;   // Multiple for each list expansion
+
+  public:
+    /* Constructor */
+    MyList() {
+        arr = new int[arrCapacity];
+    }
+
+    /* Destructor */
+    ~MyList() {
+        delete[] arr;
+    }
+
+    /* Get list length (current number of elements)*/
+    int size() {
+        return arrSize;
+    }
+
+    /* Get list capacity */
+    int capacity() {
+        return arrCapacity;
+    }
+
+    /* Access element */
+    int get(int index) {
+        // If the index is out of bounds, throw an exception, as below
+        if (index < 0 || index >= size())
+            throw out_of_range("Index out of bounds");
+        return arr[index];
+    }
+
+    /* Update element */
+    void set(int index, int num) {
+        if (index < 0 || index >= size())
+            throw out_of_range("Index out of bounds");
+        arr[index] = num;
+    }
+
+    /* Add element at the end */
+    void add(int num) {
+        // When the number of elements exceeds capacity, trigger the expansion mechanism
+        if (size() == capacity())
+            extendCapacity();
+        arr[size()] = num;
+        // Update the number of elements
+        arrSize++;
+    }
+
+    /* Insert element in the middle */
+    void insert(int index, int num) {
+        if (index < 0 || index >= size())
+            throw out_of_range("Index out of bounds");
+        // When the number of elements exceeds capacity, trigger the expansion mechanism
+        if (size() == capacity())
+            extendCapacity();
+        // Move all elements after `index` one position backward
+        for (int j = size() - 1; j >= index; j--) {
+            arr[j + 1] = arr[j];
+        }
+        arr[index] = num;
+        // Update the number of elements
+        arrSize++;
+    }
+
+    /* Remove element */
+    int remove(int index) {
+        if (index < 0 || index >= size())
+            throw out_of_range("Index out of bounds");
+        int num = arr[index];
+        // Move all elements after `index` one position forward
+        for (int j = index; j < size() - 1; j++) {
+            arr[j] = arr[j + 1];
+        }
+        // Update the number of elements
+        arrSize--;
+        // Return the removed element
+        return num;
+    }
+
+    /* Extend list */
+    void extendCapacity() {
+        // Create a new array with a length multiple of the original array by extendRatio
+        int newCapacity = capacity() * extendRatio;
+        int *tmp = arr;
+        arr = new int[newCapacity];
+        // Copy all elements from the original array to the new array
+        for (int i = 0; i < size(); i++) {
+            arr[i] = tmp[i];
+        }
+        // Free memory
+        delete[] tmp;
+        arrCapacity = newCapacity;
+    }
+
+    /* Convert the list to a Vector for printing */
+    vector<int> toVector() {
+        // Only convert elements within valid length range
+        vector<int> vec(size());
+        for (int i = 0; i < size(); i++) {
+            vec[i] = arr[i];
+        }
+        return vec;
+    }
+};
+
+/* Driver Code */
+int main() {
+    /* Initialize list */
+    MyList *nums = new MyList();
+    /* Add element at the end */
+    nums->add(1);
+    nums->add(3);
+    nums->add(2);
+    nums->add(5);
+    nums->add(4);
+    cout << "List nums = ";
+    vector<int> vec = nums->toVector();
+    printVector(vec);
+    cout << "Capacity = " << nums->capacity() << ", length = " << nums->size() << endl;
+
+    /* Insert element in the middle */
+    nums->insert(3, 6);
+    cout << "Insert the number 6 at index 3, resulting in nums = ";
+    vec = nums->toVector();
+    printVector(vec);
+
+    /* Remove element */
+    nums->remove(3);
+    cout << "Remove the element at index 3, resulting in nums = ";
+    vec = nums->toVector();
+    printVector(vec);
+
+    /* Access element */
+    int num = nums->get(1);
+    cout << "Access the element at index 1, obtained num = " << num << endl;
+
+    /* Update element */
+    nums->set(1, 0);
+    cout << "Update the element at index 1 to 0, resulting in nums = ";
+    vec = nums->toVector();
+    printVector(vec);
+
+    /* Test expansion mechanism */
+    for (int i = 0; i < 10; i++) {
+        // At i = 5, the list length will exceed the list capacity, triggering the expansion mechanism at this time
+        nums->add(i);
+    }
+    cout << "After extending, list nums = ";
+    vec = nums->toVector();
+    printVector(vec);
+    cout << "Capacity = " << nums->capacity() << ", length = " << nums->size() << endl;
+
+    // Free memory
+    delete nums;
+
+    return 0;
+}