938. Range Sum of BST (axross#148)

Author: Kohei Asai

solutions/range_sum_of_bst.ts

@@ -0,0 +1,17 @@
+import { BinaryTreeNode } from "../data_structures/binary_tree.ts";
+
+// 938. Range Sum of BST
+// https://leetcode.com/problems/range-sum-of-bst/
+export default function rangeSumBST(
+  node: BinaryTreeNode<number> | null,
+  L: number,
+  R: number
+): number {
+  if (!node) return 0;
+
+  const leftSum = node.val > L ? rangeSumBST(node.left, L, R) : 0;
+  const rightSum = node.val < R ? rangeSumBST(node.right, L, R) : 0;
+  const self = node.val >= L && node.val <= R ? node.val : 0;
+
+  return leftSum + self + rightSum;
+}

solutions/range_sum_of_bst_test.ts

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+import { test } from "https://deno.land/std/testing/mod.ts";
+import { assertStrictEq } from "https://deno.land/std/testing/asserts.ts";
+import { createBinaryTreeNode } from "../data_structures/binary_tree.ts";
+import rangeSumBST from "./range_sum_of_bst.ts";
+
+test("938. Range Sum of BST", () => {
+  assertStrictEq(
+    rangeSumBST(createBinaryTreeNode([10, 5, 15, 3, 7, null, 18]), 7, 15),
+    32
+  );
+  assertStrictEq(
+    rangeSumBST(
+      createBinaryTreeNode([10, 5, 15, 3, 7, 13, 18, 1, null, 6]),
+      6,
+      10
+    ),
+    23
+  );
+  assertStrictEq(
+    rangeSumBST(
+      createBinaryTreeNode([10, 5, 15, 3, 7, 13, 18, 1, null, 6]),
+      4,
+      12
+    ),
+    28
+  );
+  assertStrictEq(rangeSumBST(createBinaryTreeNode([1]), 1, 1), 1);
+  assertStrictEq(rangeSumBST(createBinaryTreeNode([]), 1, 1), 0);
+});