# ----------------------------------------
# GILMORE-GOMORY METHOD FOR
# CUTTING STOCK PROBLEM
# ----------------------------------------

option solver gurobi;
option solution_round 6;

model cut1.mod;
data cut1.dat;

problem Cutting_Opt: Cut, Number, Fill;
   option relax_integrality 1;
   option presolve 0;

problem Pattern_Gen: Use, Reduced_Cost, Width_Limit;
   option relax_integrality 0;
   option presolve 1;

let nPAT := 0;

for {i in WIDTHS} {
   let nPAT := nPAT + 1;
   let nbr[i,nPAT] := floor (roll_width/i);
   let {i2 in WIDTHS: i2 <> i} nbr[i2,nPAT] := 0;
   };

repeat {
   solve Cutting_Opt;

   let {i in WIDTHS} price[i] := Fill[i].dual;

   solve Pattern_Gen;

   if Reduced_Cost < -0.00001 then {
      let nPAT := nPAT + 1;
      let {i in WIDTHS} nbr[i,nPAT] := Use[i];
      }
   else break;
   };

display nbr; 
display Cut;

option Cutting_Opt.relax_integrality 0;
option Cutting_Opt.presolve 10;
solve Cutting_Opt;

display Cut;