Add C++ code for the chapter binary tree.

codes/cpp/chapter_searching/hashing_search.cpp

@@ -40,7 +40,7 @@ int main() {
     cout << "目标元素 3 的索引 = " << index << endl;
 
     /* 哈希查找（链表） */
-    ListNode* head = vectorToLinkedList(nums);
+    ListNode* head = vecToLinkedList(nums);
     // 初始化哈希表
     unordered_map<int, ListNode*> map1;
     while (head != nullptr) {

codes/cpp/chapter_searching/linear_search.cpp

@@ -42,7 +42,7 @@ int main() {
     cout << "目标元素 3 的索引 = " << index << endl;
 
     /* 在链表中执行线性查找 */
-    ListNode* head = vectorToLinkedList(nums);
+    ListNode* head = vecToLinkedList(nums);
     ListNode* node = linearSearch(head, target);
     cout << "目标结点值 3 的对应结点对象为 " << node << endl;