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Proper divisors: Difference between revisions

Proper divisors (view source)

Revision as of 21:04, 14 November 2018

378 bytes removed ,  5 years ago
m
→‎version 2: added whitespace.
(→‎{{header|Perl 6}}: Optimize, add some verbiage about optimization and concurrency)
m (→‎version 2: added whitespace.)
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<lang rexx>/*REXX program finds proper divisors (and count) of integer ranges; finds the max count.*/
parse arg bot top inc range xtra /*obtain optional arguments from the CL*/
if bot=='' | bot=="," then bot= 1 1 /*Not specified? Then use the default.*/
if top=='' | top=="," then top= 10 10 /* " " " " " " */
if inc=='' | inc=="," then inc= 1 1 /* " " " " " " */
if range=='' | range=="," then range=20000 20000 /* " " " " " " */
w=1+ max( length(top), length(bot), length(range)) /*determine the biggest number of these*/
numeric digits max(9, w) + 1) /*have enough digits for // operator.*/
@.= 'and' /*a literal used to separate #s in list*/
do n=bot to top by inc /*process the first range specified. */
q= Pdivs(n); #= words(q) /*get proper divs; get number of Pdivs.*/
if q=='∞' then #=q q /*adjust number of Pdivisors for zero. */
say right(n, max(20, w) ) 'has' center(#, 4) "proper divisors: " q
end /*n*/
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m=0 /*M ≡ maximum number of Pdivs (so far).*/
do r=1 for range /*process the second range specified. */
q= Pdivs(r); #=words(q) #= words(q) /*get proper divs; get number of Pdivs.*/
if #<m then iterate /*Less then max? Then ignore this #. */
@.#= @.# @. r; m=# /*add this Pdiv to max list; set new M.*/
end /*r*/ /* [↑] process 2nd range of integers.*/
 
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", and it's for: " subword(@.m, 3)
say /* [↓] handle any given extra numbers.*/
do i=1 for words(xtra); n= word(xtra, i) /*obtain an extra number from XTRA list*/
w= max(w, 1 + length(n) ) /*use maximum width for aligned output.*/
numeric digits max(9, 1 + length(n) ) /*have enough digits for // operator.*/
q= Pdivs(n); #=words(q) #= words(q) /*get proper divs; get number of Pdivs.*/
say right(n, max(20, w) ) 'has' center(#, 4) "proper divisors."
end /*i*/ /* [↑] support extra specified integers*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
Pdivs: procedure; parse arg x,b; x= abs(x); if x==1 then return '' /*unity?*/
odd= x // 2; if x==0 then return '∞' /*zero ?*/
ra=0 1 /* [↓] ══integer squareuse root══all, or only odd #s. ___ ___*/
q=1; do while q<=z;do qj=q*4; end2+odd by 1+odd while j*j < x /*R:divide by ansome integerintegers whichup will beto √ X */
do while q>1; q=q%4; _=z-r-q; r=r%2; if _>=0 then do; z=_; r=r+q; end
end /*while q>1*/ /* [↑] compute the integer sqrt of X.*/
a=1 /* [↓] use all, or only odd #s. ___*/
do j=2 +odd by 1 +odd to r -(r*r==x) /*divide by some integers up to √ X */
if x//j==0 then do; a=a j; b=x%j b /*if ÷, add both divisors to α & ß. */
end
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