Recently a recruiter asked me to do a coding challenge. He told me to spend twenty minutes on it. Three hours after starting, I had completed the six questions that covered things like dynamic programming, converting between integers and Roman numerals, and processing data from csv files; and I had figured out why their submission script was causing a stack overflow and let them know about the bug.
The code was clean, it passed all but a few of the hidden test cases, and the recruiter told me I scored well; and I could get back on the work I was now behind on for the day because of my naïveté. Two weeks later, the company didn't move forward with an interview.
Why is my reaction to coding challenges an allergic one? A coding challenge (completed alone) is a cheap and wide net that is can be costly for the engineers who fall into it - and yes, I’ve already done enough of them to know something is fishy.
What if I’m about to spend my best hours of the day producing free, production-quality code, and you aren’t going to honor that with something as small as a phone call from the decision maker to talk afterward? Keep in mind, usually the discussion at this point has been: “Hello.” “Hi.” . These conversations don’t look very different, and, empirically, continuing doesn’t have a great expected value.