Good evening! Here's our prompt for today.

A binary search tree is a data structure that has the following properties,

• Each node in the tree has only two children.
• The left subtree consists of nodes with values less than the root node.
• The right subtree consists of nodes with values greater than the root node.

Consider that you are given a binary search tree as root, and two integers low and high. Can you find the sum of values of all nodes that are in the inclusive range [low, high]?

This problem can be best understood visually. Consider the example below. Nodes with values between the [7, 15] range are colored orange, and the sum of values of these nodes gives us the answer.

Constraints

• The number of nodes in the tree is in the range [1, 2 * 104].
• 1 <= Node.val <= 105
• 1 <= low <= high <= 105
• All Node.val are unique.

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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    console.log('PASSED: ' + "sumRangeBST([10, 5, 15, 3, 7, 13, 18, 1, None, 6], 6, 10) should return `23`");

var assert = require('assert');

​

function TreeNode(val) {

    this.val = val

    this.left = null

    this.right = null

}

​

/**

 * @param {TreeNode} root

 * @param {number} low

 * @param {number} high

 * @return {number}

 */

function sumRangeBST(root, low, high) {

    return

}

​

try {

    let root = new TreeNode(10)

    root.left = new TreeNode(5)

    root.right = new TreeNode(15)

    root.left.left = new TreeNode(3)

    root.left.right = new TreeNode(7)

    root.right.right = new TreeNode(18)

    assert.equal(sumRangeBST(root, 7, 15), 32);

​

    console.log('PASSED: ' + "sumRangeBST([10, 5, 15, 3, 7, None, 18], 7, 15) should return `32`");

} catch (err) {

Here's our guided, illustrated walk-through.

How do I use this guide?