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+package leetcode.validate_binary_search_tree;%0A%0Aimport common.TreeNode;%0A%0Apublic class Solution %7B%0A%09%0A%09public boolean isValidBST(TreeNode root, Integer lower, Integer upper)%7B%0A%09%09if(root.left != null)%7B%0A%09%09%09if(root.left.val %3E= root.val) return false;%0A%09%09%09if(lower != null && root.left.val %3C= lower.intValue()) return false;%0A%09%09%09if(!isValidBST(root.left, lower, root.val)) return false; %0A%09%09%7D%0A%09%09if(root.right != null)%7B%0A%09%09%09if(root.right.val %3C= root.val) return false;%0A%09%09%09if(upper != null && root.right.val %3E= upper.intValue()) return false;%0A%09%09%09if(!isValidBST(root.right, root.val, upper)) return false; %0A%09%09%7D%0A%09%09return true;%0A%09%7D%0A%09%0A    public boolean isValidBST(TreeNode root) %7B%0A    %09if(root == null) return true;%0A        return isValidBST(root, null, null);%0A    %7D%0A%7D%0A

Add java solution for 98. Validate Binary Search Tree