DESAIN RUTE OPTIMAL PERMASALAHAN PENGANGKUTAN SAMPAH DI KOTA PALEMBANG MENGGUNAKAN MODEL DEMAND ROBUST COUNTERPART OPEN CAPACITATED VEHICLE ROUTING PROBLEM WITH TIME WINDOWS AND DEADLINE (DRC-OCVRPtw,d) BERBASIS LINGO 13.0 - BR.SIMANJUNTAK, ANI SAHARA (2019)