root/trunk/samples/knapsack/glpk/knapsack.mod

/* number of items */
param n, integer, >0;
/* items */
set I := 1..n;
/* item weights */
param weights{i in I}, integer, >0;
/* item sizes */
param sizes{i in I}, integer, >0;
/* knapsack size */
param capacity, integer, >0;

var usage {i in I} binary;

maximize total_weight: sum{i in I} usage[i]*weights[i];

subject to max_size: sum {i in I} usage[i]*sizes[i] <= capacity;

solve;

# Print the solution
for {i in I} printf " %i\n", usage[i];
printf "\n";
printf "optimum: %i\n", sum {i in I} usage[i] * weights[i];

end;