Added solution to problem 938 of leetcode

C++/RangeSumOfBST.cpp

@@ -0,0 +1,51 @@
+// Question:- Given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high].
+
+/**
+ * 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 solve(TreeNode* root,int low,int high,int &ans){
+        if(!root) return;
+        if(root-> val >=low && root->val <=high){ //checking if root value is in range
+            ans+=root->val;
+            solve(root->left, low, high, ans);  //recursively calling left tree
+            solve(root->right, low, high, ans);  //recursively calling right tree
+        }
+        else if(root->val> high){   //if root value is more than high, then according to BST low values won't be in right tree so search left tree
+            solve(root->left, low, high, ans);
+        }
+        else if(root->val < low){ //if root value is less than low, then according to BST low values won't be in left tree so search right tree
+            solve(root->right, low, high, ans);
+        }
+    }
+    int rangeSumBST(TreeNode* root, int low, int high) {
+        int sum = 0;
+        solve(root, low, high, sum);
+        return sum;
+    }
+};
+
+// Test Case 1
+// Input root = [10,5,15,3,7,null,18]
+// low = 7
+// high = 15
+// Excepted = 32
+// Output = 32
+
+
+// Test Case 2
+// Input root = [10,5,15,3,7,13,18,1,null,6]
+// low = 6
+// high = 10
+// Expected = 23
+// Output = 23

README.md

@@ -260,6 +260,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 98   | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)                       | [Javascript](./JavaScript/98.Validate-Binary-Search-Tree.js)                                                     | _O(log(n))_ | _O(log(n))_ | Medium     | Binary Tree                                    |
 | 684  | [Redundant Connection](https://leetcode.com/problems/redundant-connection/)                                     | [Java](./Java/Redundant-Connection/redundant-connection.java)                                                    | _O(N)_      | _O(N)_      | Medium     | Tree, Union Find                               |
 | 102 | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/)   |[C++](./C++/Binary-Tree-Level-Order-Traversal.cpp)| _O(n)_      | _O(n)_      | Medium     | Binary Tree, map                                    |      |
+| 938 | [Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/)   |[C++](./C++/RangeSumOfBST.cpp)| _O(n)_      | _O(n)_      | Easy     | Binary Search Tree                                    |      |
 
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