  The stretched Littlewood-Richardson coefficient $c^{t\nu}_{t\lambda,t\mu}$
was conjectured by King, Tollu, and Toumazet to be a polynomial function in
$t.$ It was shown to be true by Derksen and Weyman using semi-invariants of
quivers. Later, Rassart used Steinberg's formula, the hive conditions, and the
Kostant partition function to show a stronger result that
$c^{\nu}_{\lambda,\mu}$ is indeed a polynomial in variables $\nu, \lambda, \mu$
provided they lie in certain polyhedral cones. Motivated by Rassart's approach,
we give a short alternative proof of the polynomiality of
$c^{t\nu}_{t\lambda,t\mu}$ using Steinberg's formula and a simple argument
about the chamber complex of the Kostant partition function.
