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# 16.5 BSTs as Sets and Maps

We can use a BST to implement the `Set` ADT. If we use a BST, we can decrease the runtime of `contains` to $$\log(n)$$ because of the BST property which enables us to use binary search!

We can also make a binary tree into a map by having each BST node hold `(key,value)` pairs instead of singular values. We will compare each element's key in order to determine where to place it within our tree.