Range Sum of BST
Description
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]
.
Example 1:
![](https://assets.leetcode.com/uploads/2020/11/05/bst1.jpg)
Input: root = [10,5,15,3,7,null,18], low = 7, high = 15 Output: 32 Explanation: Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32.
Example 2:
![](https://assets.leetcode.com/uploads/2020/11/05/bst2.jpg)
Input: root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10 Output: 23 Explanation: Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23.
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.
Solution(javascript)
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @param {number} low
* @param {number} high
* @return {number}
*/
var rangeSumBST = function(root, low, high) {
let sum = 0;
function dfs(root, low, high) {
if(root == null) return null;
if(low <= root.val && root.val <= high) sum += root.val;
if(low < root.val) dfs(root.left, low, high);
if(high > root.val) dfs(root.right, low, high);
}
dfs(root, low, high);
return sum;
};