validate-binary-search-tree solution

Author: togo26

validate-binary-search-tree/togo26.js

@@ -0,0 +1,14 @@
+/**
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+// TC: O(n) / SC: Best O(height) - Worst O(n)
+var isValidBST = function (root) {
+  function traverse(node, min, max) {
+    if (!node) return true;
+    if (!(min < node.val && node.val < max)) return false;
+    return traverse(node.left, min, node.val) && traverse(node.right, node.val, max);
+  }
+
+  return traverse(root, -Infinity, Infinity);
+};