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Re: Find combination of numbers whose sum equals X

by johngg (Canon)
on Nov 20, 2020 at 17:38 UTC ( #11123915=note: print w/replies, xml ) Need Help??


in reply to Find combination of numbers whose sum equals X

The word "combination" in the title brought Algorithm::Combinatorics to mind. I'm not sure if duplicate sums, e.g. the several 5+5+10+80 combinations in the third example, should all be shown but I have eliminated them. This code

use strict; use warnings; use feature qw{ say }; use Algorithm::Combinatorics qw{ combinations }; use List::Util qw{ sum }; my @tests = ( { target => 100, values => [ 1, 99, 2, 40, 50, 100, 60, 90, 3, 5, 95, 100 ], }, { target => 10, values => [ 1, 3, 2, 4 ], }, { target => 100, values => [ 5, 5, 5, 5, 10, 15, 80, 99 ], }, ); foreach my $rhTest ( @tests ) { say qq{\nFind sums from }, join( q{, }, @{ $rhTest->{ values } } ), qq{ making $rhTest->{ target }}; say for do { my %seen; grep { ! $seen{ $_ } ++ } grep { $_ == $rhTest->{ target } } @{ $rhTest->{ values } }; }; for my $sumsOf ( 2 .. scalar @{ $rhTest->{ values } } ) { my $combIter = combinations( $rhTest->{ values }, $sumsOf ); my %seen; while ( my $raComb = $combIter->next() ) { next if $seen{ join q{+}, sort { $a <=> $b } @{ $raComb } +} ++; say join q{+}, @{ $raComb } if $rhTest->{ target } == sum @{ $raComb }; } } }

produces

Find sums from 1, 99, 2, 40, 50, 100, 60, 90, 3, 5, 95, 100 making 100 100 1+99 40+60 5+95 2+3+95 2+90+3+5 2+40+50+3+5 Find sums from 1, 3, 2, 4 making 10 1+3+2+4 Find sums from 5, 5, 5, 5, 10, 15, 80, 99 making 100 5+15+80 5+5+10+80 5+5+5+5+80

I hope this is helpful.

Cheers,

JohnGG

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