I have been doing leetcoding, competitive programming for several years. I think I solved around 600 questions in Leetcode. When I was doing all of this, I was using C for it. I don't even remember why I choose C for it. But at this point I have practiced in C way too much. And at this point it's not that trivial for me to switch over to another language on the fly.

For a lot of these leetcode style questions, using C is almost like using my muscle memory. If you ask me to implement a BFS on a 2D grid, I can type out the bare bones code without even thinking. This gives me a significant time advantage when I am interviewing. It also ensures that I don't make trivial mistakes.

Here's problem with this though. Yesterday I was interviewing for a Java developer position and they gave me a top-k problem and told me to solve it in Java. Given some rows of data, find the top 10 elements using some criteria. And I simply did not remember the priority queue syntax at that point. I did look at the priority queue syntax before the interview. But I just could not recollect it. I could have used sorting instead of priority queue. But the interviewer immediately shot that idea down saying that he might add new rows. He was against the idea of re-running the sort algorithm everytime. He didn't like the idea of doing a binary search on the input array and inserting an item into the correct spot. He had that priority queue solution in his mind and he was trying to get me to code up a priority queue. Obviously he was against the idea of creating a PQ from scratch. He wanted to see me use PQ in that interview. I wrote out the solution in C at this point, but he was like "This is a Java job"

At work I heavily use Java, I also have experience with Scala, Python & Javascript. but I never had to use priority queue for anything at work. I have shipped a crap ton of code in Java at work. But I use Java/Python/Scala/JS for a different purpose at work.