David Lowes

Write a function that determines if a tree is a BST

function isBST(curNode, minval, maxval){
    if (curNode == null) {
        return true;
    }
    return (
        (minval == null || minval <= curNode.Value) &&
        (maxval == null || maxval >= curNode.Value) &&
        isBST(curNode.Left, minval, curNode.Value) &&
        isBST(curNode.Right, curNode.Value, maxval)
    );
}