Ok, thank you, I only tried one of the test cases, when I tried all of them I found the problem. It actually had nothing to do with the sort function lol

When you say "works fine" did you use the test case that your code fails on or did you pick a different one?
Testing one input does not prove that it works for all input, and if you're going to say that the difference is a different environment then everything else should stay the same. When you change multiple things you can't say which of them is the cause.

Suggestion: print out (and make sure to flush stdout) the input you get, and debug that locally.

Works fine on my computer, here I get UndefinedBehaviorSanitizer:DEADLYSIGNAL when I change a comparison operator in a sort function...