Free memory after removing

a node from a LinkedList or TreeNode.

codes/cpp/chapter_array_and_linkedlist/linked_list.cpp

@@ -21,6 +21,8 @@ void remove(ListNode* n0) {
     ListNode* P = n0->next;
     ListNode* n1 = P->next;
     n0->next = n1;
+    // 释放内存
+    delete P;
 }
 
 /* 访问链表中索引为 index 的结点 */

codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp

@@ -50,7 +50,10 @@ public:
     int poll() {
         int num = peek();
         // 删除头结点
+        ListNode *tmp = front;
         front = front->next;
+        // 释放内存
+        delete tmp; 
         queSize--;
         return num;
     }

codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp

@@ -39,7 +39,10 @@ public:
     /* 出栈 */
     int pop() {
         int num = top();
+        ListNode *tmp = stackTop;
         stackTop = stackTop->next;
+        // 释放内存
+        delete tmp;
         stkSize--;
         return num;
     }

codes/cpp/chapter_tree/binary_search_tree.cpp

@@ -96,11 +96,13 @@ public:
             // 删除结点 cur
             if (pre->left == cur) pre->left = child;
             else pre->right = child;
+            // 释放内存
+            delete cur;
         }
         // 子结点数量 = 2
         else {
             // 获取中序遍历中 cur 的下一个结点
-            TreeNode* nex = min(cur->right);
+            TreeNode* nex = getInOrderNext(cur->right);
             int tmp = nex->val;
             // 递归删除结点 nex
             remove(nex->val);
@@ -110,8 +112,8 @@ public:
         return cur;
     }
 
-    /* 获取最小结点 */
-    TreeNode* min(TreeNode* root) {
+    /* 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况） */
+    TreeNode* getInOrderNext(TreeNode* root) {
         if (root == nullptr) return root;
         // 循环访问左子结点，直到叶结点时为最小结点，跳出
         while (root->left != nullptr) {

codes/cpp/chapter_tree/binary_tree.cpp

@@ -33,6 +33,7 @@ int main() {
     PrintUtil::printTree(n1);
     // 删除结点 P
     n1->left = n2;
+    delete P;  // 释放内存
     cout << endl << "删除结点 P 后\n" << endl;
     PrintUtil::printTree(n1);