Added Leetcode Problem:226 codeharborhub#908

Author: Anshika14528

dsa-solutions/lc-solutions/0200-0299/0226-invert-binary-search-tree.md

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+---
+id: invert binary search tree
+title: Invert Binary Search Tree
+sidebar_label: 0226 Invert Binary Search Tree
+tags:
+  - tree
+  - recursion
+  - LeetCode
+  - C++
+description: "This is a solution to the Invert Binary Search Tree problem on LeetCode."
+---
+
+## Problem Description
+
+Given the root of a binary tree, invert the tree, and return its root.
+
+### Examples
+
+**Example 1:**
+
+```
+
+Input: root = [4,2,7,1,3,6,9]
+Output:  [4,7,2,9,6,3,1]
+```
+
+**Example 2:**
+
+```
+Input: root = [2,1,3]
+Output: [2,3,1]
+```
+
+```
+Input: root =  []
+Output:  []
+```
+
+### Constraints
+
+- The number of nodes in the tree is in the range $[0, 100]$.
+- `-100 <= Node.val <= 100`
+
+### Approach 
+
+To solve this problem(invert BST) we will use recursion(call function repeatedly) and  temporary tree node(t) for swapping.
+
+#### Code in C++
+
+```cpp
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+   void invert(TreeNode* root){
+        if(root==NULL){
+            return;
+        }
+        TreeNode* t;
+        t=root->right;
+        root->right=root->left;
+        root->left=t;
+        invert(root->left);
+        invert(root->right);
+    }
+    TreeNode* invertTree(TreeNode* root) {
+        invert(root);
+        return root;
+
+    }
+};
+```
+
+