**“Range Sum of BST” Javascript solution Cheat Sheet**

The Range Sum of the BST challenge is in the easy category and is a good start for understanding more challenging algorithms using trees as a data structure. I will focus on explaining a solution that works and not on the O time and space complexity.

**Challenge:** “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].”LeetCode

**Note:**

//Binary search tree data structure.//Two integers low and high defined the range.//Return sum of values within the range, including range values.

**Example:**

Input: root = [10,5,16,3,6,null,19], low = 6, high = 16Nodes 6, 10, and 16 are in the range [6, 16]. 6 + 10 + 16 =32 Output: 3210

/\

5 16

/\ \

3 6 19

**Explanation:**

//Loop trought the left and right branch of the tree,//check if node value is within the defined range,//if it is then add it to the sum within the range,// return the final sum of range values.

**1. Sum result will be pushed to an array**

`sum = [];`

**2. Create a helper method for the node**

`function dsf(node){`

**3. If no node return null**

`if(!node) return null;`

**4. Starting by left branch then right**

`dsf(node.left)`

`dsf(node.right)`

**5. If the node value is greater or equal to low and smaller or equal to high it is within the range**

`if (node.val >= low && node.val <= high){`

**6. If within the range, push node value to the sum**

`sum.push(node.val)`

`console.log(sum)`

**7. Return sum by addition nodes values using reduce**

`return sum.reduce((a,b)=> a+b,0 )`

**Solution :**

var rangeSumBST = function(root, low, high) {sum = [];function dsf(node){if(!node) return null;dsf(node.left)high to be within the rangeif (node.val >= low && node.val <= high){sum.push(node.val)}dsf(node.right)}dsf(root)console.log(sum)return sum.reduce((a,b)=> a+b,0 )};