...also, i sincerely hope you don't subscribe to this ridiculous notion that you should try to solve EVERY problem in 2 minutes or less. (lots of people seem to believe this, even though it's crazy.)
remember, "2 minutes" is the AVERAGE time for a quant problem.
as with any other average, there will be lots of data points below this one, AND lots of data points above it.
if you take longer than that, it's fine... as long as you don't sit there staring at the problem. if you stop making actual progress, then, quit and try some other approach.