Does changing variables and doing some minor changes also detected at end of the contest ?
I think its not detected because some problems have same solution by all users(all created same structure of logic,But different variables name and types)…
Its not detected perhaps. As many problems have same or similar solution for many users specially the adhoc and cakewalk category of problems.
N.B- However i would advice to refrain from it as codechef is a platform for learning and doing palgirism would is least expected.
Actually, as far as I know, it is detected.
The plagiarism checker takes many things into account, not just the code. The similar solutions of cakewalk problems go undetected because they choose to do so. The cakewalk problem usually have a 1-2 simple solutions and clashes are bound to happen. Hence many a times, the cakewalks are exempted from strong plagiarism checks.
Sometimes there is unfair plagiarism with some other user whom we don’t even know…just because our code matches?
Yes some such cases are reported.