Commit 72e26f1

@@ -0,0 +1,78 @@
+require "spec_helper"
+
+describe "problem eight" do
+  #The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.
+
+  let(:data) do
+    <<-BLAH
+    73167176531330624919225119674426574742355349194934
+    96983520312774506326239578318016984801869478851843
+    85861560789112949495459501737958331952853208805511
+    12540698747158523863050715693290963295227443043557
+    66896648950445244523161731856403098711121722383113
+    62229893423380308135336276614282806444486645238749
+    30358907296290491560440772390713810515859307960866
+    70172427121883998797908792274921901699720888093776
+    65727333001053367881220235421809751254540594752243
+    52584907711670556013604839586446706324415722155397
+    53697817977846174064955149290862569321978468622482
+    83972241375657056057490261407972968652414535100474
+    82166370484403199890008895243450658541227588666881
+    16427171479924442928230863465674813919123162824586
+    17866458359124566529476545682848912883142607690042
+    24219022671055626321111109370544217506941658960408
+    07198403850962455444362981230987879927244284909188
+    84580156166097919133875499200524063689912560717606
+    05886116467109405077541002256983155200055935729725
+    71636269561882670428252483600823257530420752963450
+    BLAH
+  end
+
+  #Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?
+  class MassScan
+    attr_reader :data, :position
+
+    def initialize(data)
+      @data = data.gsub(/ /, '').gsub(/\n/, '')
+      @position = 0
+    end
+
+    def scan(digits:)
+      queue = []
+      max = 0
+
+      fill(queue)
+      puts queue.inspect
+      result = sum(queue)
+      puts result
+      max = queue.dup if result > max
+      puts max
+
+      max
+    end
+
+    private
+
+    def fill(queue)
+      4.times do |n|
+        queue.shift
+        queue.push(data[position])
+        puts position
+        position += 1
+      end
+      puts queue
+    end
+
+    def sum(queue)
+      queue.inject(0) do |memo, n|
+        memo += n
+      end
+    end
+  end
+
+  subject { MassScan.new(data) }
+
+  it "returns the four digits that produce the greatest product" do
+    expect(subject.scan(digits: 4)).to eql(9989)
+  end
+end