* 
* GAMS program for knapsack
* David Pisinger
* 

$eolcom //
option iterlim=999999999,reslim=300,optcr=0.0,optca=0.0,solprint=OFF,mip=XPRESS;

SETS
	i	'genstand'      
                /i1,  i2,  i3,  i4,  i5,  i6,  i7,  i8,  i9,  i10/

PARAMETERS
	b	'max energi'
       / 25 /

        e(i)	'energi'
      /	i1     12
	i2      7
	i3      8
	i4     11
	i5     15
	i6     12
	i7      4
	i8      6
	i9     13
	i10    14 /

        s(i)	'smag'
      /	i1     13
	i2     12
	i3      7
	i4      8
	i5     10
	i6     21
	i7      4
	i8     12
	i9      8
	i10    16 / ;

VARIABLES
 	 z  			'total smag som skal optimeres'
binary variables x(i)   	'beslutningsvariable'

EQUATIONS
	smag  	'total smag'
	energi	'total energi' ;

smag   ..	z =E= sum(i, s(i)*x(i)) ;
energi ..	sum(i, e(i)*x(i)) =L= b ;

MODEL knapsack /ALL/ ; 
knapsack.workspace=10;
SOLVE knapsack USING MIP MAXIMIZING z ;

DISPLAY z.L;  // value of the objective
DISPLAY x.L;  // x.L  : Level, i.e. result