Re: Need a 40 LOC (ignoring comments) to be shorter -- suggestions wanted

Verbose and inefficient, but there was a 10 minute limit :slight_smile:

class Gen
include Enumerable
def each
(3…7).each do |c1|
(3…7).each do |c2| next if [c1].include? c2
(3…7).each do |c3| next if [c1,c2].include? c3
(3…7).each do |c4| next if [c1,c2,c3].include? c4
(3…7).each do |c5| next if [c1,c2,c3,c4].include? c5
yield β€œ#{c1}#{c2}#{c3}”.to_i, β€œ#{c4}#{c5}”.to_i
end
end
end
end
end
end
end

puts Gen.new.min { |(a,b),(c,d)| ab <=> cd }

Damn this is annoying :slight_smile:

OK here’s another one, this time with a recursive permutation generator.
It
should be easier to modify to other variations of this problem. (However
it
currently doesn’t permute arrays with duplicate elements)

class Permutations
include Enumerable

def initialize(src)
@data = src
end

def each(&blk)
permute([], @data.to_a, &blk)
end

def permute(base, rest, &blk)
if rest.empty?
yield base
else
rest.each { |elem| permute(base + [elem], rest - [elem], &blk) }
end
end
end

p Permutations.new(3…7).
map { |data| [data[0,3].join.to_i, data[3,2].join.to_i] }.
min { |(a,b),(c,d)| ab <=> cd }

My final offering, inspired by Park H.'s solution.

p (34567…76543).map { |x| [x/100 * (x%100), x] if x.to_s !~
/[^3-7]|(.).*\1/ }.compact.min

=> [product, nnnmm]

Regards,

Brian.

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