Ex7 5

$\def\abs#1{|#1|}\def\i{\mathbf {i}}\def\ket#1{|{#1}\rangle}\def\bra#1{\langle{#1}|}\def\braket#1#2{\langle{#1}|{#2}\rangle}\def\tr{\mathord{\mbox{tr}}}\mathbf{Exercise\ 7.5}$

Show that a classical solution to Simon's problem requires $O(2^{n/2})$ calls to the black box, and describe such a classical algorithm.