From: Giampiero Zanchi <cidza@...>
Date: 2008-11-05T22:29:22+09:00
Subject: Re: Combination of numbers in an array that add up to x

Hae Lee wrote:
> Objective: Find list of values in an array that adds up to a specific
> sum.
> -
> I have a list of values in an array:
> [2429.63, 497.87, 51.96, 59.43, 138.4, 66.22, 28.74, 1.75, 2075.13,
> 556.14, 112.56, 116.5, 84.41, 55.97, 139.07, 24.46]
> 
> I want to find a combination among these numbers that adds up to a total
> sum of:
> 3435.78
> 
> I was hoping a one-liner in irb would do the trick but I haven't found a
> method, etc. that will help me do this.  Thoughts regarding?

Hi from Italy, this is my first post on this forum; I am a ruby 
beginner, so I took your question as an exercise; the following is the 
one solution I found (integer values):
175, 11256, 11650, 13840, 13907, 49787, 242963

v = [2429.63, 497.87, 51.96, 59.43, 138.4, 66.22, 28.74, 1.75, 2075.13,
556.14, 112.56, 116.5, 84.41, 55.97, 139.07, 24.46]
goal = 343578
v.map! {|x| (x*100).to_i}
v.sort!
def to_binary(i)
  bin_vett = []
  loop do
    bin_vett.push(i % 2)
    i = i / 2
    break if i == 0
  end
  bin_vett.reverse
end
n = 2 ** v.size
n.times do |i|
  b = to_binary(i)
  sum = 0
  b.each_index do |j|
    sum += v[j] if b[j] == 1
  end
  if sum == goal then
    b.each_index do |j|
      print "#{v[j]}  " if b[j] == 1
    end
  end
end
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