I was given a coding challenge, which was broken up into two parts. First, you had a time limit to complete a set of Leetcode-esque programming problems. Following completion of the problems, you had to explain your process to arrive at a solution.

After about a week, I went into back-to-back technical and behavioral interviews (over the phone), which were both around 30 minutes. The behavioral interview was like any other HR interview (strengths/weaknesses, why you want to work for the company, talk about your projects, etc.). The technical interview was mainly about OOP.

What are the four pillars of OOP?