best-offer

Best offer

You are given three offers, each represented with the type int option. An offer is Some(x) means that x is the amount of the offer, while None means that no offer is made.

Write a function of type:

best_offer : int option -> int option -> int option -> int option

that takes three offers and returns the highest one. If none of the offers are valid (i.e., all are None), the function should return None.

Examples

best_offer (Some 100) (Some 200) (Some 150) = Some 200

best_offer (Some 100) None (Some 150) = Some 150

best_offer None None None = None

best_offer None (Some 300) None = Some 300