Knapsack problem/Continuous: Difference between revisions

<lang rexx>/*REXX program solves the (continuous) burglar's knapsack problem. */

@.= /*═══════ name weight value ══════*/

@.1 = 'flitch 4 30 '

@.2 = 'beef 3.8 36 '

@.3 = 'pork 5.4 43 '

@.4 = 'greaves 2.4 45 '

@.5 = 'brawn 2.5 56 '

@.6 = 'welt 3.7 67 '

@.7 = 'ham 3.6 90 '

@.8 = 'salami 3 95 '

@.9 = 'sausage 5.9 98 '

parse arg maxW d . /*get possible argsarguments from the C.L. */

if maxW=='' | maxW==',' then maxW=15 /*the burglar's knapsack maxmaximum weight. */

if d=='' | d==',' then d= 3 /*#number of decimal digits in FORMAT. */

wL=d+length('weight'); nL=d+length('total weight'); vL=d+length('value')

do #=1 while @.#\==''; parse var @.# n.# w.# v.# .

end /*#*/ /* [↑] assign item to separate lists. */

#=#-1 /*#: is the number of items in @ list.*/

call show 'unsorted item list' /*display the header and the @ list.*/

call sortD /*invoke usingsort a(which descendingsorts sortdescending).*/

do j=1 for # while totW<maxW; f=1 /*grabprocess items. */

if totW+w.j>=maxW then f=(maxW-totW)/w.j /*calccalculate fract.*/

totW=totW+w.j*f; totV=totV+v.j*f /*add──►totsadd ───► totals.*/

end /*j*/ /*↑show [↑] show item.*/

call sep; say; t='t' /* [↓] $ supresses suppresses trailing Θszeroes.*/

exit /*stick a fork in it, we're all done. */

/*──────────────────────────────────one─liner subroutines──────────────────────subroutines─────────────────────*/

hdr: say; say; say center(arg(1),50,'─'); say; call title; call sep; return

sep: call sy copies('═',nL), copies("═",wL), copies('═',vL); return

show: call hdr arg(1); do j=1 for #; call syf n.j,w.j,v.j; end; return

sy: say left('',9) left(arg(1),nL) right(arg(2),wL) right(arg(3),vL); return

syf: call sy arg(1), $(format(arg(2),,d)), $(format(arg(3),,d)); return

title: call sy center('item',nL), center("weight",wL), center('value',vL); return

$: x=arg(1);if pos(.,x)>1 then x=left(strip(strip(x,'T't,0),,.),length(x));return x

/*──────────────────────────────────SORTD subroutine───────────────────────────subroutine──────────────────────────*/

sortD: do sorts=2 to #; _n a=n.sorts; _w!=w.sorts; u=v.s /* [↓] _v=v.sort this is a /*descending sort. */

do k=sorts-1 by -1 to 1 while v.k/w.k<_vu/_w /*order items!;?=k+1;n.*/?=n.k;w.?=w.k;v.?=v.k;end

p?=k+1; n.p?=n.ka; w.p?=w.k!; v.p?=v.k /*shuffle 'em.*/u

end /*k*/ /*[↓] last ones*/

return a=k+1; n.a=_n; w.a=_w;/* ↑↑↑ sort algorithm is OK v.a=_vfor small /*place itemarrays. */</lang>