diff --git a/subtree-of-another-tree/reeseo3o.js b/subtree-of-another-tree/reeseo3o.js
new file mode 100644
index 000000000..c66a40670
--- /dev/null
+++ b/subtree-of-another-tree/reeseo3o.js
@@ -0,0 +1,18 @@
+// Time Complexity: O(n*m)
+// Space Complexity: O(n+m)
+
+const isSubtree = (root, subRoot) => {
+  const isSame = (a, b) => {
+    if (!a && !b) return true;
+    if (!a || !b) return false;
+    if (a.val !== b.val) return false;
+    return isSame(a.left, b.left) && isSame(a.right, b.right);
+  };
+
+  if (!root) return false;
+  return (
+    isSame(root, subRoot) ||
+    isSubtree(root.left, subRoot) ||
+    isSubtree(root.right, subRoot)
+  );
+};