Add an SOS constraint to the model. Please refer to this section for details on SOS constraints.
|GRBSOS||addSOS (||const GRBVar*||vars,|
vars: Array of variables that participate in the SOS constraint.
weights: Weights for the variables in the SOS constraint.
len: Number of members in the new SOS set (length of vars and weights arrays).
type: SOS type (can be GRB_SOS_TYPE1 or GRB_SOS_TYPE2).
New SOS constraint.