It will return true even when the tree is not a valid BST. Consider the case where a leaf in the left subtree contains a value higher than the root of the tree.
@doesnotexist great point. With that said, that is not the official solution. There is no official solution. This is a community driven repo. Anyone can contribute.
https://github.com/opentable/ot-daily-algorithm/commit/e811a...
It will return true even when the tree is not a valid BST. Consider the case where a leaf in the left subtree contains a value higher than the root of the tree.