This is the question we asked to all the students at careers fairs up and down the country last month:
You have two fuses that burn unevenly for exactly one hour each. How can you use two fuses to measure 45 minutes?
And here is the answer!
Take one fuse and light it at one end. At the same moment, light both ends of the other fuse. As soon as the fuse you lit twice has burned out (i.e. exactly half an hour) light the first fuse at the other end. That will then take another 15 minutes to burn out completely. (And 30+15 is 45 last time we checked!)
This is a great example of how a seemingly difficult question can be quickly simplified if you find the right approach to thinking about it. In this case we can try breaking it down - if you first ask how to measure 30 minutes - the trick of lighting both ends suddenly becomes more obvious. From there it is a simple extrapolation to do that a second time to halve the time again.
Why we like ‘thinking’ problems
Development is really about thinking. You don’t just get a brief and start coding - if only! The interesting part is figuring out the right approach. This takes a bit of exploration, a lot of collaboration, and creativity. And trust us, it’s worth getting this part right!
So when we recruit, we look for more than code credentials - we look for ‘thinking’ developers. Apply to us if you think that’s you.
A few harder problems
- With two fuses, how can you measure approximately 20 minutes?
- How many fuses would you need to measure approximately 55 minutes?
Let us know if you get the answers, and look out for us at next year's careers fairs!