Problem 112

112.rb

@@ -0,0 +1,36 @@
+require 'pp'
+
+def bouncy(n)
+  digits = n.to_s.chars.map(&:to_i)
+  return false if digits.length == 1
+  if digits[0] < digits[1]
+    directionality = 'ascending'
+  elsif digits[0] == digits[1]
+    directionality = 'equal'
+  else
+    directionality = 'descending'
+  end
+  1.upto(digits.length-2) do |i|
+    if directionality == 'equal'
+      if digits[i] < digits[i+1]
+        directionality = 'ascending'
+      elsif digits[i] > digits[i+1]
+        directionality = 'descending'
+      end
+    else
+      return true if (directionality == 'ascending' && digits[i] > digits[i+1]) || (directionality == 'descending' && digits[i] < digits[i+1])
+    end
+  end
+  false
+end
+
+count = 0
+bouncy = 0
+bouncy_ratio = 0
+while bouncy_ratio != 0.99
+  count += 1
+  bouncy += 1 if bouncy(count)
+  bouncy_ratio = bouncy.to_f/count
+end
+
+pp count