So, as someone who spends maybe 20% of their time hiring, it's still a very effective screen. You wouldn't believe how many people can't do it. People at big companies, respected places. It's surprising.
I used a different screen (having people make change based on an arbitrary amount, so if the input was 81, you'd return [25, 25, 25, 5, 1], as we were in the USA) and it was also helpful. I didn't track the number of people that it stymied though.
Yah, that's also a good one. I like the variant that asks how many different ways you can make change for a given amount and a given array of currencies.
(I always feel weird talking about interview questions publicly, but honestly anyone who prepares that diligently deserves to go to the next stage. If anyone's reading this because they're preparing for an interview with me and I ask this question, just mention this comment and I'll be impressed.)
