  We give a quantitative characterization of the pairs of weights $(w,v)$ for
which the dyadic version of the one-sided Hardy-Littlewood maximal operator
satisfies a restricted weak $(p,p)$ type inequality, for $1\leq p<\infty$. More
precisely, given any measurable set $E_0$ the estimate \[w(\{x\in \mathbb{R}^n:
M^{+,d}(\mathcal{X}_{E_0})(x)>t\})\leq
\frac{C[(w,v)]_{A_p^{+,d}(\mathcal{R})}^p}{t^p}v(E_0)\] holds if and only if
the pair $(w,v)$ belongs to $A_p^{+,d}(\mathcal{R})$, that is
\[\frac{|E|}{|Q|}\leq
[(w,v)]_{A_p^{+,d}(\mathcal{R})}\left(\frac{v(E)}{w(Q)}\right)^{1/p}\] for
every dyadic cube $Q$ and every measurable set $E\subset Q^+$. The proof
follows some ideas appearing in [Sheldy Ombrosi, \emph{Weak weighted
inequalities for a dyadic one-sided maximal function in {$\Bbb R^n$}}, Proc.
Amer. Math. Soc. \textbf{133} (2005), no.~6, 1769--1775].
  We also obtain a similar quantitative characterization for the non-dydadic
case in $\mathbb{R}^2$ by following the main ideas in [L.~Forzani, F.~J.
Mart\'{\i}n-Reyes, and S.~Ombrosi, \emph{Weighted inequalities for the
two-dimensional one-sided {H}ardy-{L}ittlewood maximal function}, Trans. Amer.
Math. Soc. \textbf{363} (2011), no.~4, 1699--1719].
