Recently I was interviewing a candidate having 6+ years of experience highlighting “strong knowledge in data structures, their operations, and algorithms” in the resume.
Me: “Imagine that you are given the list of all 200 countries, and their properties like ISD codes, shortcodes, TLDs, etc. How will you store this in memory?”
The candidate: “I will use an ArrayList”
Me: “What about using a Map or HashMap?”
The candidate: “Why using a Map? A list is enough. I never had to use a Map in my entire career of 6+ years”.
Me (astounded): “Your resume says that you are good at data structures. What are the data structures that you use in your day-to-day programming job?”
The candidate burst out laughing and replied: “Nobody uses data structures these days. They are all just theories only!”