How do we use a queue?

Python, Java and C++ each ship a fast queue — you'll almost never write one from scratch in an interview. JavaScript is the exception. Here's what to use in each language, what the methods are called, and the traps that cost people marks.

The built-in queue in each language

The same small job in all four: put some numbers in a queue, then take them all out. They come out in the order they went in.