  This paper deals with an optimal control problem and describes the reachable
set for the scalar 1-D conservation laws with discontinuous flux. Regarding the
optimal control problem we first prove the existence of a minimizer and then we
prescribe an algorithm to compute it. The same method also applies to compute
the initial data control. The proof relies on the explicit formula for the
conservation laws with the discontinuous flux and finer properties of the
characteristics.
