feat: azl397985856#226 add C++ implementation (azl397985856#134)

Author: raof01

problems/226.invert-binary-tree.md

@@ -39,7 +39,7 @@ Google: 90% of our engineers use the software you wrote (Homebrew), but you can
 
 ## 代码
 
-* 语言支持：JS，Python
+* 语言支持：JS，Python，C++
 
 Javascript Code:
 
@@ -150,3 +150,34 @@ class Solution:
                 stack.append(node.right)
         return root
 ```
+C++ Code：
+```C++
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode* invertTree(TreeNode* root) {
+        if (root == NULL) return root;
+        auto q = queue<TreeNode*>();
+        q.push(root);
+        while (!q.empty()) {
+            auto n = q.front(); q.pop();
+            swap(n->left, n->right);
+            if (n->left != nullptr) {
+                q.push(n->left);
+            }
+            if (n->right != nullptr) {
+                q.push(n->right);
+            }
+        }
+        return root;
+    }
+};
+```