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

en/codes/cpp/chapter_heap/CMakeLists.txt

@@ -0,0 +1,3 @@
+add_executable(heap heap.cpp)
+add_executable(my_heap my_heap.cpp)
+add_executable(top_k top_k.cpp)

en/codes/cpp/chapter_heap/heap.cpp

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+/**
+ * File: heap.cpp
+ * Created Time: 2023-01-19
+ * Author: LoneRanger(836253168@qq.com)
+ */
+
+#include "../utils/common.hpp"
+
+void testPush(priority_queue<int> &heap, int val) {
+    heap.push(val); // Push the element into heap
+    cout << "\nAfter element " << val << " is added to the heap" << endl;
+    printHeap(heap);
+}
+
+void testPop(priority_queue<int> &heap) {
+    int val = heap.top();
+    heap.pop();
+    cout << "\nAfter the top element " << val << " is removed from the heap" << endl;
+    printHeap(heap);
+}
+
+/* Driver Code */
+int main() {
+    /* Initialize the heap */
+    // Initialize min-heap
+    // priority_queue<int, vector<int>, greater<int>> minHeap;
+    // Initialize max-heap
+    priority_queue<int, vector<int>, less<int>> maxHeap;
+
+    cout << "\nThe following test case is for max-heap" << endl;
+
+    /* Push the element into heap */
+    testPush(maxHeap, 1);
+    testPush(maxHeap, 3);
+    testPush(maxHeap, 2);
+    testPush(maxHeap, 5);
+    testPush(maxHeap, 4);
+
+    /* Access heap top element */
+    int peek = maxHeap.top();
+    cout << "\nTop element of the heap is " << peek << endl;
+
+    /* Pop the element at the heap top */
+    testPop(maxHeap);
+    testPop(maxHeap);
+    testPop(maxHeap);
+    testPop(maxHeap);
+    testPop(maxHeap);
+
+    /* Get heap size */
+    int size = maxHeap.size();
+    cout << "\nNumber of elements in the heap is " << size << endl;
+
+    /* Determine if heap is empty */
+    bool isEmpty = maxHeap.empty();
+    cout << "\nIs the heap empty " << isEmpty << endl;
+
+    /* Enter list and build heap */
+    // Time complexity is O(n), not O(nlogn)
+    vector<int> input{1, 3, 2, 5, 4};
+    priority_queue<int, vector<int>, greater<int>> minHeap(input.begin(), input.end());
+    cout << "After inputting the list and building a min-heap" << endl;
+    printHeap(minHeap);
+
+    return 0;
+}

en/codes/cpp/chapter_heap/my_heap.cpp

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+/**
+ * File: my_heap.cpp
+ * Created Time: 2023-02-04
+ * Author: LoneRanger (836253168@qq.com), what-is-me (whatisme@outlook.jp)
+ */
+
+#include "../utils/common.hpp"
+
+/* Max-heap */
+class MaxHeap {
+  private:
+    // Using a dynamic array to avoid the need for resizing
+    vector<int> maxHeap;
+
+    /* Get index of left child node */
+    int left(int i) {
+        return 2 * i + 1;
+    }
+
+    /* Get index of right child node */
+    int right(int i) {
+        return 2 * i + 2;
+    }
+
+    /* Get index of parent node */
+    int parent(int i) {
+        return (i - 1) / 2; // Integer division down
+    }
+
+    /* Start heapifying node i, from bottom to top */
+    void siftUp(int i) {
+        while (true) {
+            // Get parent node of node i
+            int p = parent(i);
+            // When "crossing the root node" or "node does not need repair", end heapification
+            if (p < 0 || maxHeap[i] <= maxHeap[p])
+                break;
+            // Swap two nodes
+            swap(maxHeap[i], maxHeap[p]);
+            // Loop upwards heapification
+            i = p;
+        }
+    }
+
+    /* Start heapifying node i, from top to bottom */
+    void siftDown(int i) {
+        while (true) {
+            // Determine the largest node among i, l, r, noted as ma
+            int l = left(i), r = right(i), ma = i;
+            if (l < size() && maxHeap[l] > maxHeap[ma])
+                ma = l;
+            if (r < size() && maxHeap[r] > maxHeap[ma])
+                ma = r;
+            // If node i is the largest or indices l, r are out of bounds, no further heapification needed, break
+            if (ma == i)
+                break;
+            swap(maxHeap[i], maxHeap[ma]);
+            // Loop downwards heapification
+            i = ma;
+        }
+    }
+
+  public:
+    /* Constructor, build heap based on input list */
+    MaxHeap(vector<int> nums) {
+        // Add all list elements into the heap
+        maxHeap = nums;
+        // Heapify all nodes except leaves
+        for (int i = parent(size() - 1); i >= 0; i--) {
+            siftDown(i);
+        }
+    }
+
+    /* Get heap size */
+    int size() {
+        return maxHeap.size();
+    }
+
+    /* Determine if heap is empty */
+    bool isEmpty() {
+        return size() == 0;
+    }
+
+    /* Access heap top element */
+    int peek() {
+        return maxHeap[0];
+    }
+
+    /* Push the element into heap */
+    void push(int val) {
+        // Add node
+        maxHeap.push_back(val);
+        // Heapify from bottom to top
+        siftUp(size() - 1);
+    }
+
+    /* Element exits heap */
+    void pop() {
+        // Empty handling
+        if (isEmpty()) {
+            throw out_of_range("Heap is empty");
+        }
+        // Swap the root node with the rightmost leaf node (swap the first element with the last element)
+        swap(maxHeap[0], maxHeap[size() - 1]);
+        // Remove node
+        maxHeap.pop_back();
+        // Heapify from top to bottom
+        siftDown(0);
+    }
+
+    /* Print heap (binary tree)*/
+    void print() {
+        cout << "Array representation of the heap:";
+        printVector(maxHeap);
+        cout << "Tree representation of the heap:" << endl;
+        TreeNode *root = vectorToTree(maxHeap);
+        printTree(root);
+        freeMemoryTree(root);
+    }
+};
+
+/* Driver Code */
+int main() {
+    /* Initialize max-heap */
+    vector<int> vec{9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2};
+    MaxHeap maxHeap(vec);
+    cout << "\nEnter list and build heap" << endl;
+    maxHeap.print();
+
+    /* Access heap top element */
+    int peek = maxHeap.peek();
+    cout << "\nTop element of the heap is " << peek << endl;
+
+    /* Push the element into heap */
+    int val = 7;
+    maxHeap.push(val);
+    cout << "\nAfter element " << val << " is added to the heap" << endl;
+    maxHeap.print();
+
+    /* Pop the element at the heap top */
+    peek = maxHeap.peek();
+    maxHeap.pop();
+    cout << "\nAfter the top element " << peek << " is removed from the heap" << endl;
+    maxHeap.print();
+
+    /* Get heap size */
+    int size = maxHeap.size();
+    cout << "\nNumber of elements in the heap is " << size << endl;
+
+    /* Determine if heap is empty */
+    bool isEmpty = maxHeap.isEmpty();
+    cout << "\nIs the heap empty " << isEmpty << endl;
+
+    return 0;
+}

en/codes/cpp/chapter_heap/top_k.cpp

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+/**
+ * File: top_k.cpp
+ * Created Time: 2023-06-12
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Using heap to find the largest k elements in an array */
+priority_queue<int, vector<int>, greater<int>> topKHeap(vector<int> &nums, int k) {
+    // Initialize min-heap
+    priority_queue<int, vector<int>, greater<int>> heap;
+    // Enter the first k elements of the array into the heap
+    for (int i = 0; i < k; i++) {
+        heap.push(nums[i]);
+    }
+    // From the k+1th element, keep the heap length as k
+    for (int i = k; i < nums.size(); i++) {
+        // If the current element is larger than the heap top element, remove the heap top element and enter the current element into the heap
+        if (nums[i] > heap.top()) {
+            heap.pop();
+            heap.push(nums[i]);
+        }
+    }
+    return heap;
+}
+
+// Driver Code
+int main() {
+    vector<int> nums = {1, 7, 6, 3, 2};
+    int k = 3;
+
+    priority_queue<int, vector<int>, greater<int>> res = topKHeap(nums, k);
+    cout << "The largest " << k << " elements are:";
+    printHeap(res);
+
+    return 0;
+}