Range Sum of BST

Description

Given the root node of a binary search tree, return the sum of values of all nodes with value between L and R (inclusive).

The binary search tree is guaranteed to have unique values.

 

Example 1:

Input: root = [10,5,15,3,7,null,18], L = 7, R = 15
Output: 32

Example 2:

Input: root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
Output: 23

 

Note:

1. The number of nodes in the tree is at most 10000.
2. The final answer is guaranteed to be less than 2^31.

Solution(javascript)

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} L
 * @param {number} R
 * @return {number}
 */
const rangeSumBST = (root, L, R) => {
  let sum = 0
  const aux = (node) => {
    if (!node) {
      return
    }
    if (node.val >= L) {
      aux(node.left)
    }
    if (node.val >= L && node.val <= R) {
      sum += node.val
    }
    if (node.val <= R) {
      aux(node.right)
    }
  }
  aux(root)
  return sum
}