Rings and Disks aka Omega 2013

Author: mrhead

omega2013.rb

@@ -0,0 +1,40 @@
+# http://blog.codility.com/2013/07/omega-2013-codility-programming.html
+# rings and disks
+
+def rings_and_disks(a, b)
+  count = 0
+
+  # transform well
+  a.each_index do |i|
+    next if i == 0
+    a[i] = a[i - 1] < a[i] ? a[i - 1] : a[i]
+  end
+
+  # place disks
+  b.each do |disk|
+    while a.any?
+      ring = a.pop
+      if disk <= ring
+        count += 1
+        break
+      end
+    end
+  end
+  count
+end
+
+require 'minitest/autorun'
+
+class Tests < MiniTest::Unit::TestCase
+  def test_example_input
+    assert_equal 4, rings_and_disks([5, 6, 4, 3, 6, 2, 3], [2, 3, 5, 2, 4])
+  end
+
+  def test_small_rings
+    assert_equal 0, rings_and_disks([1, 2, 3], [5, 1, 1])
+  end
+
+  def test_all_rings
+    assert_equal 5, rings_and_disks([5, 4, 3, 2, 1], [1, 2, 3, 4, 5])
+  end
+end