Add validate binary search Solution - s0ooo0k

Author: s0ooo0k

validate-binary-search-tree/s0ooo0k.java

@@ -0,0 +1,14 @@
+/*
+ * 시간복잡도 : O(n)
+ */
+
+class Solution {
+    public boolean isValidBST(TreeNode root) {
+        return valid(root, Long.MIN_VALUE, Long.MAX_VALUE);
+    }
+    private boolean valid(TreeNode node, long min, long max) {
+        if(node==null) return true;
+        if(node.val <= min || node.val >=max) return false;
+        return valid(node.left, min, node.val) && valid(node.right, node.val, max);
+    }
+}