Validate Binary Search Tree solution

Author: kimjunyoung90

validate-binary-search-tree/kimjunyoung90.java

@@ -0,0 +1,11 @@
+public class kimjunyoung90 {
+    public boolean isValidBST(TreeNode root) {
+        return validate(root, Long.MIN_VALUE, Long.MAX_VALUE);
+    }
+
+    public boolean validate(TreeNode node, long min, long max) {
+        if(node == null) return true;
+        if(node.val <= min || node.val >= max) return false;
+        return validate(node.left, min, node.val) && validate(node.right, node.val, max);
+    }
+}