I'm trying to refresh myself on quantum algorithms and have been skimming Childs and van Dam's [2008 RMP paper](http://arxiv.org/abs/0812.0380v1) among other things. From my preliminary surfing it looks like the known quantum algorithms still essentially fall into (in that their nontrivial quantum aspect is governed by) four major classes, viz.


1. Linear
algebra
2. Quantum Fourier transform and hidden
subgroup problems
3. Quantum search
4. Quantum simulation/annealing


and I'm wondering: does this classification clearly miss anything?


(NB. Because I'm hoping for answers that discuss *why* a given algorithm does not fall into one of these classes, I'm not making this CW.)



Are there any known quantum algorithms that clearly fall outside a few narrow classes?
Does the [Farhi-Goldstone-Gutman game tree evaluation algorithm](http://arxiv.org/abs/quant-ph/0702144) and the extensions of it fall into one of these classes? You might put it in quantum simulation/annealing because of the technique used, but I think that would be a mistake. You might also put it in quantum search because it doesn't give a super-polynomial speed-up, but it has a very different flavor than all the other quantum search algorithms.


