Advent of Code 2020 - Day 1: finding 2 or 3 numbers that add up to 2020
Your code is well done and shows familiarity with Rust.
The best I can do is comment on some parts of the code and provide two small, concrete pieces of advice. There is very little room for improvement in the code.
I see your Vecs in function parameters are well motivated. The one in find_triple is motivated by the need to do pop, and the one in find_pair just follows the other for consistency between parts of the task.
The decision to introduce Number as a type alias is ok, and works and looks fine, but keep in mind that it adds an extra mental hop for the reader.
Return types
Acting by intuition I'd change the return types to have const-length arrays instead of tuples. This brings attention to the fact that the array/tuple is homogeneous. I would change:
-&gt; Option&lt;(Number, Number, Number)&gt; and return Some((a, b, number));
to
-&gt; Option&lt;[Number; 3]&gt; and return Some([a, b, number]);
Typo?
It's good to be correct and consistent in naming. The function name is find_triple - but 'triple' is not a noun, 'triplet' is.