Sharing our solutions to Leetcode problems.

Hi there! We are a pair of software engineers practicing for algorithm interviews. We thought it'd be good to share our solutions, in case some else on the Internet (like you!) come across the same problem(s) and wants some hints. For each problem we're trying to do two things:

- solve it using as many ways as we can think of, and
- record our thought process with as little typing as possible.

The second point tends to be self-conflicting, so let us know if anything needs more clarity!