They asked me to write the skeleton for the method of the class containing the lambda which sparked a lot of confusion on both sides, as I didn't understand their instructions, but eventually I got to writing. I wrote the lambda, and they wanted me to also call in the function and remember it and call it later in the function, which I've never encountered and got confused again. Their frustration is now showing a little. We moved to the singleton. I told them I have no clue since I only wrote singletons in Java. The main interviewer scoffed and loudly announced that the interview is not worth continuing. We continued anyway. The next question had 4 allocations and 4 deletions and I had to identify how they worked. I wrongly answered 3 of them, as they were not standard. The final question was a very weird piece of code containing virtual methods and some C++ magic which I had no clue how it worked, they insisited I'm supposed to know and after getting the answer wrong 5 times they gave up.