Spotify Web Developer interview questions

A head hunter contacted me through LinkedIn asking for a resumé, introduced me to the job description with was pretty much matching my profile. A week later I did a one hour technical interview through Skype where I was asked about http requests, threads, memories, java x php, typed vars x untyped vars, apache x nginx and other subjects related to web development in general. Another week later I was contacted by a js/php dev leader to test me using an online colab PHP editor and I there were three tests to be done: - Identify unique integers in an array. (easy) - Sort an array (easy). (without using array_sort). - Check nested strings following this examples: (intermediate). '{}' -> is nested '{{}}' -> is nested '{}{}' -> is nested '{}}{' -> not nested '}{{}' -> not nested '{{{}}}' -> is nested