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Power set: Difference between revisions
→{{header|REXX}}: added the REXX language. -- ~~~~
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(→{{header|REXX}}: added the REXX language. -- ~~~~) |
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}
</lang>
=={{header|REXX}}==
<lang rexx>/*REXX program to display a power set, items may be anything (no blanks)*/
parse arg set /*let user specify the items. */
if set=='' then set='one two three four' /*None specified? Use default*/
N=words(set) /*number of items in the list.*/
ps='{}' /*start with a null power set.*/
do chunk=1 for N /*traipse through the items. */
ps=ps combN(N,chunk) /*N items, a CHUNK at a time. */
end /*chunk*/
w=words(ps)
do k=1 for w /*show combinations, one/line.*/
say right(k,length(w)) word(ps,k)
end /*k*/
exit /*stick a fork in it, we done.*/
/*─────────────────────────────────────$COMBN subroutine────────────────*/
combN: procedure expose $ set; parse arg x,y; $=
!.=0; base=x+1; bbase=base-y; ym=y-1; do p=1 for y; !.p=p; end
do j=1; L=
do d=1 for y; _=!.d; L=L','word(set,_); end
$=$ '{'strip(L,'L',",")'}'
!.y=!.y+1; if !.y==base then if .combU(ym) then leave
end /*j*/
return strip($) /*return with partial powerset*/
.combU: procedure expose !. y bbase; parse arg d; if d==0 then return 1
p=!.d; do u=d to y; !.u=p+1
if !.u==bbase+u then return .combU(u-1)
p=!.u
end /*u*/
return 0</lang>
'''output''' when using the default input:
<pre style="overflow:scroll">
1 {}
2 {one}
3 {two}
4 {three}
5 {four}
6 {one,two}
7 {one,three}
8 {one,four}
9 {two,three}
10 {two,four}
11 {three,four}
12 {one,two,three}
13 {one,two,four}
14 {one,three,four}
15 {two,three,four}
16 {one,two,three,four}
</pre>
=={{header|Ruby}}==
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