Online judge is competitive programming like https://open.kattis.com/ https://open.kattis.com/ or CodeWars or CodeForces meaning a server that takes your source

Online judge is competitive programming like https://open.kattis.com/ https://open.kattis.com/ or CodeWars or CodeForces meaning a server that takes your source, compiles and runs it, tests if you satisfied all the req of the challenge. There's books for this https://cpbook.net/#CP4content https://cpbook.net/#CP4content and despite leetfree claims of being 'useless because no online judge in interview' there is actually 2-3 judges sitting there in the interview performing the same function, telling you if your code does not satisfy the problem requirements