Add destructors to the C++ codes.

codes/cpp/chapter_array_and_linkedlist/array.cpp

@@ -23,6 +23,8 @@ int* extend(int* nums, int size, int enlarge) {
     for (int i = 0; i < size; i++) {
         res[i] = nums[i];
     }
+    // 释放内存
+    delete[] nums;
     // 返回扩展后的新数组
     return res;
 }
@@ -82,10 +84,7 @@ int main() {
     
     /* 长度扩展 */
     int enlarge = 3;
-    int* res = extend(nums, size, enlarge);
-    int* temp = nums;
-    nums = res;
-    delete[] temp;
+    nums = extend(nums, size, enlarge);
     size += enlarge;
     cout << "将数组长度扩展至 8 ，得到 nums = ";
     PrintUtil::printArray(nums, size);
@@ -107,5 +106,9 @@ int main() {
     int index = find(nums, size, 3);
     cout << "在 nums 中查找元素 3 ，得到索引 = " << index << endl;
 
+    // 释放内存
+    delete[] arr;
+    delete[] nums;
+
     return 0;
 }

codes/cpp/chapter_array_and_linkedlist/linked_list.cpp

@@ -83,5 +83,8 @@ int main() {
     int index = find(n0, 2);
     cout << "链表中值为 2 的结点的索引 = " << index << endl;
 
+    // 释放内存
+    freeMemoryLinkedList(n0);
+
     return 0;
 }

codes/cpp/chapter_array_and_linkedlist/my_list.cpp

@@ -20,6 +20,11 @@ public:
         nums = new int[numsCapacity];
     }
 
+    /* 析构函数 */
+    ~MyList() {
+        delete[] nums;
+    }
+
     /* 获取列表长度（即当前元素数量）*/
     int size() {
         return numsSize;
@@ -90,14 +95,14 @@ public:
     void extendCapacity() {
         // 新建一个长度为 size * extendRatio 的数组，并将原数组拷贝到新数组
         int newCapacity = capacity() * extendRatio;
-        int* extend = new int[newCapacity];
+        int* tmp = nums;
+        nums = new int[newCapacity];
         // 将原数组中的所有元素复制到新数组
         for (int i = 0; i < size(); i++) {
-            extend[i] = nums[i];
+            nums[i] = tmp[i];
         }
-        int* temp = nums;
-        nums = extend;
-        delete[] temp;
+        // 释放内存
+        delete[] tmp;
         numsCapacity = newCapacity;
     }
 
@@ -160,5 +165,8 @@ int main() {
     PrintUtil::printVector(vec);
     cout << "容量 = " << list->capacity() << " ，长度 = " << list->size() << endl;
 
+    // 释放内存
+    delete list;
+
     return 0;
 }

codes/cpp/chapter_computational_complexity/leetcode_two_sum.cpp

@@ -56,5 +56,9 @@ int main() {
     cout << "方法二 res = ";
     PrintUtil::printVector(res);
 
+    // 释放内存
+    delete slt1;
+    delete slt2;
+
     return 0;
 }

codes/cpp/chapter_computational_complexity/space_complexity.cpp

@@ -18,7 +18,7 @@ void constant(int n) {
     const int a = 0;
     int b = 0;
     vector<int> nums(10000);
-    ListNode* node = new ListNode(0);
+    ListNode node(0);
     // 循环中的变量占用 O(1) 空间
     for (int i = 0; i < n; i++) {
         int c = 0;
@@ -34,9 +34,9 @@ void linear(int n) {
     // 长度为 n 的数组占用 O(n) 空间
     vector<int> nums(n);
     // 长度为 n 的列表占用 O(n) 空间
-    vector<ListNode*> nodes;
+    vector<ListNode> nodes;
     for (int i = 0; i < n; i++) {
-        nodes.push_back(new ListNode(i));
+        nodes.push_back(ListNode(i));
     }
     // 长度为 n 的哈希表占用 O(n) 空间
     unordered_map<int, string> map;
@@ -98,5 +98,8 @@ int main() {
     TreeNode* root = buildTree(n);
     PrintUtil::printTree(root);
 
+    // 释放内存
+    freeMemoryTree(root);
+
     return 0;
 }

codes/cpp/chapter_stack_and_queue/array_queue.cpp

@@ -21,6 +21,10 @@ public:
         nums = new int[capacity];
     }
 
+    ~ArrayQueue() {
+        delete[] nums;
+    }
+
     /* 获取队列的容量 */
     int capacity() {
         return cap;
@@ -117,5 +121,8 @@ int main() {
         PrintUtil::printVector(queue->toVector());
     }
 
+    // 释放内存
+    delete queue;
+
     return 0;
 }

codes/cpp/chapter_stack_and_queue/array_stack.cpp

@@ -78,5 +78,8 @@ int main() {
     bool empty = stack->empty();
     cout << "栈是否为空 = " << empty << endl;
 
+    // 释放内存
+    delete stack;
+
     return 0;
 }

codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp

@@ -19,6 +19,11 @@ public:
         queSize = 0;
     }
 
+    ~LinkedListQueue() {
+        delete front;
+        delete rear;
+    }
+
     /* 获取队列的长度 */
     int size() {
         return queSize;
@@ -108,5 +113,8 @@ int main() {
     bool empty = queue->empty();
     cout << "队列是否为空 = " << empty << endl;
 
+    // 释放内存
+    delete queue;
+
     return 0;
 }

codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp

@@ -18,6 +18,10 @@ public:
         stkSize = 0;
     }
 
+    ~LinkedListStack() {
+        freeMemoryLinkedList(stackTop);
+    }
+
     /* 获取栈的长度 */
     int size() {
         return stkSize;
@@ -97,5 +101,8 @@ int main() {
     bool empty = stack->empty();
     cout << "栈是否为空 = " << empty << endl;
 
+    // 释放内存
+    delete stack;
+
     return 0;
 }

codes/cpp/chapter_tree/binary_search_tree.cpp

@@ -17,6 +17,10 @@ public:
         root = buildTree(nums, 0, nums.size() - 1);  // 构建二叉搜索树
     }
 
+    ~BinarySearchTree() {
+        freeMemoryTree(root);
+    }
+
     /* 获取二叉树根结点 */
     TreeNode* getRoot() {
         return root;
@@ -152,5 +156,8 @@ int main() {
     cout << endl << "删除结点 4 后，二叉树为\n" << endl;
     PrintUtil::printTree(bst->getRoot());
 
+    // 释放内存
+    delete bst;
+
     return 0;
 }

codes/cpp/chapter_tree/binary_tree.cpp

@@ -37,5 +37,8 @@ int main() {
     cout << endl << "删除结点 P 后\n" << endl;
     PrintUtil::printTree(n1);
 
+    // 释放内存
+    freeMemoryTree(n1);
+
     return 0;
 }

codes/cpp/include/ListNode.hpp

@@ -48,3 +48,18 @@ ListNode* getListNode(ListNode *head, int val) {
     }
     return head;
 }
+
+/**
+ * @brief Free the memory allocated to a linked list
+ * 
+ * @param cur 
+ */
+void freeMemoryLinkedList(ListNode *cur) {
+    // 释放内存
+    ListNode *pre;
+    while (cur != nullptr) {
+        pre = cur;
+        cur = cur->next;
+        delete pre;
+    }
+}

codes/cpp/include/TreeNode.hpp

@@ -68,3 +68,16 @@ TreeNode *getTreeNode(TreeNode *root, int val) {
     TreeNode *right = getTreeNode(root->right, val);
     return left != nullptr ? left : right;
 }
+
+/**
+ * @brief Free the memory allocated to a tree
+ * 
+ * @param root 
+ */
+void freeMemoryTree(TreeNode *root) {
+    if (root == nullptr) return;
+    freeMemoryTree(root->left);    
+    freeMemoryTree(root->right);
+    // 释放内存
+    delete root;    
+}