[UPD] Fix prune_cuts when only one cut is available

Author: frapac

src/SDDPoptimize.jl

@@ -538,8 +538,12 @@ Return:
 function prune_cuts(model::SPModel, params::SDDPparameters, V::PolyhedralFunction)
     ncuts = V.numCuts
     # Find all active cuts:
-    active_cuts = Bool[is_cut_active(model, i, V, params.solver) for i=1:ncuts]
-    return PolyhedralFunction(V.betas[active_cuts], V.lambdas[active_cuts, :], sum(active_cuts))
+    if ncuts > 1
+        active_cuts = Bool[is_cut_active(model, i, V, params.solver) for i=1:ncuts]
+        return PolyhedralFunction(V.betas[active_cuts], V.lambdas[active_cuts, :], sum(active_cuts))
+    else
+        return V
+    end
 end