HackerRank are simple exercices which can be done in a few minutes to one hour [online IDE, short single-file code]. It's trivial for anyone who can program, [except the screening tests in limited time with hard (or custom) exercises].
The bootcamp people with good ranking are likely people who started programming a long time ago, but never professionally. It's a given that they must be able to solve simple exercises.
HackerRank are simple exercices which can be done in a few minutes to one hour [online IDE, short single-file code]. It's trivial for anyone who can program, [except the screening tests in limited time with hard (or custom) exercises].
The bootcamp people with good ranking are likely people who started programming a long time ago, but never professionally. It's a given that they must be able to solve simple exercises.