用Lingo怎样求解整数规划模型…急用！ 大家帮帮忙谢了…

Question

用Lingo怎样求解整数规划模型…急用！
例：minz=x11+x12+x13+x14+x21+x22+x23
s.t a=5*x11+4*x12+3*x13+2*x14+3*x21+2*x22+x23>=20
1/6a<=3*x21+2*x22+x23<=1/3a
x11<=2
x12<=2
x13<=3
x14<=1
x21<=3
x22<=3
x23<=4
x11,x12,x13,x14,x21,x22,x23>=0且都为整数

Answer 1

model:
min=x11+x12+x13+x14+x21+x22+x23;
a-5*x11+4*x12+3*x13+2*x14+3*x21+2*x22+x23=0;
a>=20;
1/6*a-3*x21+2*x22+x23<=0;
3*x21+2*x22+x23-1/3*a<=0;
x11<=2;
x12<=2;
x13<=3;
x14<=1;
x21<=3;
x22<=3;
x23<=4;
@gin(x11);@gin(x12);@gin(x13);
@gin(x14);@gin(x21);@gin(x22);
@gin(x23);
end

Answer 2

@gin(x11)