Time: 0 ms (100%), Space: 54.1 MB (16.02%) - LeetHub

Author: chappdev2019

0098-validate-binary-search-tree/0098-validate-binary-search-tree.js

@@ -0,0 +1,15 @@
+var isValidBST = function (root) {
+    let prev = null; 
+    return dfs(root); 
+
+    function dfs(root) {
+        if (root == null) return true;
+        if (!dfs(root.left)) return false; 
+        if (prev !== null && root.val <= prev.val) { 
+            return false; 
+        }
+        prev = root; 
+        return dfs(root.right); 
+
+    }
+};