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

en/codes/cpp/chapter_searching/CMakeLists.txt

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+add_executable(binary_search binary_search.cpp)
+add_executable(binary_search_insertion binary_search_insertion.cpp)
+add_executable(binary_search_edge binary_search_edge.cpp)
+add_executable(two_sum two_sum.cpp)

en/codes/cpp/chapter_searching/binary_search.cpp

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+/**
+ * File: binary_search.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Binary search (double closed interval) */
+int binarySearch(vector<int> &nums, int target) {
+    // Initialize double closed interval [0, n-1], i.e., i, j point to the first element and last element of the array respectively
+    int i = 0, j = nums.size() - 1;
+    // Loop until the search interval is empty (when i > j, it is empty)
+    while (i <= j) {
+        int m = i + (j - i) / 2; // Calculate midpoint index m
+        if (nums[m] < target)    // This situation indicates that target is in the interval [m+1, j]
+            i = m + 1;
+        else if (nums[m] > target) // This situation indicates that target is in the interval [i, m-1]
+            j = m - 1;
+        else // Found the target element, thus return its index
+            return m;
+    }
+    // Did not find the target element, thus return -1
+    return -1;
+}
+
+/* Binary search (left closed right open interval) */
+int binarySearchLCRO(vector<int> &nums, int target) {
+    // Initialize left closed right open interval [0, n), i.e., i, j point to the first element and the last element +1 of the array respectively
+    int i = 0, j = nums.size();
+    // Loop until the search interval is empty (when i = j, it is empty)
+    while (i < j) {
+        int m = i + (j - i) / 2; // Calculate midpoint index m
+        if (nums[m] < target)    // This situation indicates that target is in the interval [m+1, j)
+            i = m + 1;
+        else if (nums[m] > target) // This situation indicates that target is in the interval [i, m)
+            j = m;
+        else // Found the target element, thus return its index
+            return m;
+    }
+    // Did not find the target element, thus return -1
+    return -1;
+}
+
+/* Driver Code */
+int main() {
+    int target = 6;
+    vector<int> nums = {1, 3, 6, 8, 12, 15, 23, 26, 31, 35};
+
+    /* Binary search (double closed interval) */
+    int index = binarySearch(nums, target);
+    cout << "Index of target element 6 =" << index << endl;
+
+    /* Binary search (left closed right open interval) */
+    index = binarySearchLCRO(nums, target);
+    cout << "Index of target element 6 =" << index << endl;
+
+    return 0;
+}

en/codes/cpp/chapter_searching/binary_search_edge.cpp

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+/**
+ * File: binary_search_edge.cpp
+ * Created Time: 2023-08-04
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Binary search for insertion point (with duplicate elements) */
+int binarySearchInsertion(const vector<int> &nums, int target) {
+    int i = 0, j = nums.size() - 1; // Initialize double closed interval [0, n-1]
+    while (i <= j) {
+        int m = i + (j - i) / 2; // Calculate midpoint index m
+        if (nums[m] < target) {
+            i = m + 1; // Target is in interval [m+1, j]
+        } else {
+            j = m - 1; // First element less than target is in interval [i, m-1]
+        }
+    }
+    // Return insertion point i
+    return i;
+}
+
+/* Binary search for the leftmost target */
+int binarySearchLeftEdge(vector<int> &nums, int target) {
+    // Equivalent to finding the insertion point of target
+    int i = binarySearchInsertion(nums, target);
+    // Did not find target, thus return -1
+    if (i == nums.size() || nums[i] != target) {
+        return -1;
+    }
+    // Found target, return index i
+    return i;
+}
+
+/* Binary search for the rightmost target */
+int binarySearchRightEdge(vector<int> &nums, int target) {
+    // Convert to finding the leftmost target + 1
+    int i = binarySearchInsertion(nums, target + 1);
+    // j points to the rightmost target, i points to the first element greater than target
+    int j = i - 1;
+    // Did not find target, thus return -1
+    if (j == -1 || nums[j] != target) {
+        return -1;
+    }
+    // Found target, return index j
+    return j;
+}
+
+/* Driver Code */
+int main() {
+    // Array with duplicate elements
+    vector<int> nums = {1, 3, 6, 6, 6, 6, 6, 10, 12, 15};
+    cout << "\nArray nums = ";
+    printVector(nums);
+
+    // Binary search for left and right boundaries
+    for (int target : {6, 7}) {
+        int index = binarySearchLeftEdge(nums, target);
+        cout << "The leftmost index of element " << target << " is " << index << endl;
+        index = binarySearchRightEdge(nums, target);
+        cout << "The rightmost index of element " << target << " is " << index << endl;
+    }
+
+    return 0;
+}

en/codes/cpp/chapter_searching/binary_search_insertion.cpp

@@ -0,0 +1,66 @@
+/**
+ * File: binary_search_insertion.cpp
+ * Created Time: 2023-08-04
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Binary search for insertion point (no duplicate elements) */
+int binarySearchInsertionSimple(vector<int> &nums, int target) {
+    int i = 0, j = nums.size() - 1; // Initialize double closed interval [0, n-1]
+    while (i <= j) {
+        int m = i + (j - i) / 2; // Calculate midpoint index m
+        if (nums[m] < target) {
+            i = m + 1; // Target is in interval [m+1, j]
+        } else if (nums[m] > target) {
+            j = m - 1; // Target is in interval [i, m-1]
+        } else {
+            return m; // Found target, return insertion point m
+        }
+    }
+    // Did not find target, return insertion point i
+    return i;
+}
+
+/* Binary search for insertion point (with duplicate elements) */
+int binarySearchInsertion(vector<int> &nums, int target) {
+    int i = 0, j = nums.size() - 1; // Initialize double closed interval [0, n-1]
+    while (i <= j) {
+        int m = i + (j - i) / 2; // Calculate midpoint index m
+        if (nums[m] < target) {
+            i = m + 1; // Target is in interval [m+1, j]
+        } else if (nums[m] > target) {
+            j = m - 1; // Target is in interval [i, m-1]
+        } else {
+            j = m - 1; // First element less than target is in interval [i, m-1]
+        }
+    }
+    // Return insertion point i
+    return i;
+}
+
+/* Driver Code */
+int main() {
+    // Array without duplicate elements
+    vector<int> nums = {1, 3, 6, 8, 12, 15, 23, 26, 31, 35};
+    cout << "\nArray nums = ";
+    printVector(nums);
+    // Binary search for insertion point
+    for (int target : {6, 9}) {
+        int index = binarySearchInsertionSimple(nums, target);
+        cout << "The insertion point index for element " << target << " is " << index << endl;
+    }
+
+    // Array with duplicate elements
+    nums = {1, 3, 6, 6, 6, 6, 6, 10, 12, 15};
+    cout << "\nArray nums = ";
+    printVector(nums);
+    // Binary search for insertion point
+    for (int target : {2, 6, 20}) {
+        int index = binarySearchInsertion(nums, target);
+        cout << "The insertion point index for element " << target << " is " << index << endl;
+    }
+
+    return 0;
+}

en/codes/cpp/chapter_searching/hashing_search.cpp

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+/**
+ * File: hashing_search.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Hash search (array) */
+int hashingSearchArray(unordered_map<int, int> map, int target) {
+    // Hash table's key: target element, value: index
+    // If the hash table does not contain this key, return -1
+    if (map.find(target) == map.end())
+        return -1;
+    return map[target];
+}
+
+/* Hash search (linked list) */
+ListNode *hashingSearchLinkedList(unordered_map<int, ListNode *> map, int target) {
+    // Hash table key: target node value, value: node object
+    // If the key is not in the hash table, return nullptr
+    if (map.find(target) == map.end())
+        return nullptr;
+    return map[target];
+}
+
+/* Driver Code */
+int main() {
+    int target = 3;
+
+    /* Hash search (array) */
+    vector<int> nums = {1, 5, 3, 2, 4, 7, 5, 9, 10, 8};
+    // Initialize hash table
+    unordered_map<int, int> map;
+    for (int i = 0; i < nums.size(); i++) {
+        map[nums[i]] = i; // key: element, value: index
+    }
+    int index = hashingSearchArray(map, target);
+    cout << "The index of target element 3 is " << index << endl;
+
+    /* Hash search (linked list) */
+    ListNode *head = vecToLinkedList(nums);
+    // Initialize hash table
+    unordered_map<int, ListNode *> map1;
+    while (head != nullptr) {
+        map1[head->val] = head; // key: node value, value: node
+        head = head->next;
+    }
+    ListNode *node = hashingSearchLinkedList(map1, target);
+    cout << "The corresponding node object for target node value 3 is " << node << endl;
+
+    return 0;
+}

en/codes/cpp/chapter_searching/linear_search.cpp

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+/**
+ * File: linear_search.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Linear search (array) */
+int linearSearchArray(vector<int> &nums, int target) {
+    // Traverse array
+    for (int i = 0; i < nums.size(); i++) {
+        // Found the target element, thus return its index
+        if (nums[i] == target)
+            return i;
+    }
+    // Did not find the target element, thus return -1
+    return -1;
+}
+
+/* Linear search (linked list) */
+ListNode *linearSearchLinkedList(ListNode *head, int target) {
+    // Traverse the list
+    while (head != nullptr) {
+        // Found the target node, return it
+        if (head->val == target)
+            return head;
+        head = head->next;
+    }
+    // If the target node is not found, return nullptr
+    return nullptr;
+}
+
+/* Driver Code */
+int main() {
+    int target = 3;
+
+    /* Perform linear search in array */
+    vector<int> nums = {1, 5, 3, 2, 4, 7, 5, 9, 10, 8};
+    int index = linearSearchArray(nums, target);
+    cout << "The index of target element 3 is " << index << endl;
+
+    /* Perform linear search in linked list */
+    ListNode *head = vecToLinkedList(nums);
+    ListNode *node = linearSearchLinkedList(head, target);
+    cout << "The corresponding node object for target node value 3 is " << node << endl;
+
+    return 0;
+}

en/codes/cpp/chapter_searching/two_sum.cpp

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+/**
+ * File: two_sum.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Method one: Brute force enumeration */
+vector<int> twoSumBruteForce(vector<int> &nums, int target) {
+    int size = nums.size();
+    // Two-layer loop, time complexity is O(n^2)
+    for (int i = 0; i < size - 1; i++) {
+        for (int j = i + 1; j < size; j++) {
+            if (nums[i] + nums[j] == target)
+                return {i, j};
+        }
+    }
+    return {};
+}
+
+/* Method two: Auxiliary hash table */
+vector<int> twoSumHashTable(vector<int> &nums, int target) {
+    int size = nums.size();
+    // Auxiliary hash table, space complexity is O(n)
+    unordered_map<int, int> dic;
+    // Single-layer loop, time complexity is O(n)
+    for (int i = 0; i < size; i++) {
+        if (dic.find(target - nums[i]) != dic.end()) {
+            return {dic[target - nums[i]], i};
+        }
+        dic.emplace(nums[i], i);
+    }
+    return {};
+}
+
+/* Driver Code */
+int main() {
+    // ======= Test Case =======
+    vector<int> nums = {2, 7, 11, 15};
+    int target = 13;
+
+    // ====== Driver Code ======
+    // Method one
+    vector<int> res = twoSumBruteForce(nums, target);
+    cout << "Method one res = ";
+    printVector(res);
+    // Method two
+    res = twoSumHashTable(nums, target);
+    cout << "Method two res = ";
+    printVector(res);
+
+    return 0;
+}