Update

Author: FeiCoding

SetMatrixZeroes/.classpath renamed to (#73)SetMatrixZeroes/.classpath

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