Determine if a Binary Tree is a Binary Search Tree (BST)

Determine if a Binary Tree is a Binary Search Tree (BST)

Problem:
Determine if a given binary tree is a Binary Search Tree (BST) or not.

Solution:

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bool isBSTHelper(BTNode T, int min, int max) {   if (T == null) return true;   if (min < T.element && T.element < max)     return isBSTHelper(T.left, min, T.element) &&            isBSTHelper(T.right, T.element, max);   else     return false; }    bool isBST(BTNode root) {    return isBSTHelper(root, INT_MIN, INT_MAX); }

 public boolean isValidBST(TreeNode root) {
        return isBST(root, Long.MIN_VALUE, Long.MAX_VALUE);
    }
   
    public boolean isBST(TreeNode root, long min, long max) {
        if(root==null)
            return true;
        if (root.val >= max || root.val <= min)
            return false;
        return isBST(root.left, min, root.val)&&isBST(root.right, root.val, max);
     
    }