Applied through online application, HR send a link to do some C++ tests, the online test is the worst OA experience ever!!!!!! You'll need to write some simple codes in Hackerrank, however before you get started, the Hackerrank told me "it is allowed to include/import some public library" but when you try to solve them, you are not, you could only edit the function body while the inclusion header is not accessible. I don't know what the heck they want for those simple questions, not allowed to include simple structure like "stack" or "map"?? Although there are ways to slove them without inclusion, but you shouldn't tell tester that "it's allowed to include some public library" at the beginning of the test, What's the meaning of those tricks?? Totally nonsense...