Working through the problems listed on HackerRank I will share my solutions here. If necessary I'll include my thought process when first given the problem and what considerations I made when thinking about Space and Time complexity.

All solutions completed using Java.

While these solutions compile, in no way should you assume these answers are 'The Best' answers, some of them may have the fastest run-time or use the lowest amount of memory. I cannot guaruntee however that all of my solutions will, and please consider this if taking notes from these solutions.