Leetcode/938

README.md

@@ -209,6 +209,7 @@
 - [901: Stock plan](problems/leetcode/901) - Monotonic stack
 - [905: Sort array by parity](problems/leetcode/905) - Easy - Array
 - [907: Sum of subarray minimums](problems/leetcode/907) - Monotonic stack
+- [938: Range sum of BST](problems/leetcode/938) - Easy - Tree
 - [941: Valid mountain array](problems/leetcode/941) - Easy - Array
 - [947 - Most stones removed with same row or column](problems/leetcode/947)
 - [976: Largest perimeter triangle](problems/leetcode/976)

problems/leetcode/938/solution.js

@@ -0,0 +1,25 @@
+/**
+ * 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}
+ */
+const rangeSumBST = (root, low, high) => {
+  let sum = 0;
+  if (root) {
+      if (low <= root.val && root.val <= high) {
+          sum += root.val;
+      }
+      sum += rangeSumBST(root.left, low, high)
+      sum += rangeSumBST(root.right, low, high);
+  }
+  return sum;
+}