  The guesswork of a quantum ensemble quantifies the minimum number of guesses
needed in average to correctly guess an unknown message encoded in the states
of the ensemble. Here, we derive sufficient conditions under which the
computation of the minimum guesswork can be recast as a discrete problem. We
show that such conditions are always satisfied for qubit ensembles with uniform
probability distribution, thus settling the problem in that case. As
applications, we compute the guesswork for any qubit regular-polygonal and
regular-polyhedral ensembles.
