亀田の回答

code_breaker/kameda/codebreaker.rb

@@ -0,0 +1,66 @@
+# -*- encoding: utf-8 -*-
+
+
+module Enumerable
+  def sum
+    self.inject(0) {|memo,i| memo + i}
+  end
+end
+
+class Object
+  def try(message)
+    self.nil? ? nil : self.send(message)
+  end
+end
+
+module Codebreaker
+  class Game
+    def initialize(output)
+      @output = output
+    end
+
+    def start(secret)
+      @secret = secret
+    end
+
+    def guess(guess)
+      secret_ary = @secret.split(//)
+      guess_ary = guess.split(//)
+
+      match_count = self.match_count(secret_ary, guess_ary)
+      real_hit_count = self.total_hit_count(secret_ary, guess_ary) - match_count
+
+      ('+' * match_count) + ('-' * real_hit_count)
+    end
+
+    def total_hit_count(secret_ary, guess_ary)
+      secret_hash = secret_ary.group_by {|char| char} # {要素 => 要素数} というハッシュを作りたいが、次善策
+      guess_hash  = guess_ary .group_by {|char| char}
+      secret_hash.map {|key, chars|
+        secret_count = chars.size
+        guess_count  = guess_hash[key].try(:size).to_i
+        [secret_count, guess_count].min
+      }.sum
+    end
+
+    def match_count(secret_ary, guess_ary)
+      secret_ary.zip(guess_ary).select {|sec, gue|
+        sec == gue
+      }.size
+    end
+
+  end
+end
+
+case $0
+when __FILE__
+  game = Codebreaker::Game.new(STDOUT)
+  game.start('1234')
+  while(code=gets.chomp)
+    puts game.guess(code)
+  end
+when /spec[^\/]*$/
+  # {spec of the implementation}
+end
+
+

code_breaker/kameda/features/codebreaker_submits_guess.feature

@@ -0,0 +1,57 @@
+Feature: codebreaker submits guess
+  The codebreaker submits a guess of four numbers. The game marks the guess with + and - signs.
+
+  For each number in the guess that matches the number and position of a number in the secret code, the mark includes one + sign. For each number in the guess that matches the number but not the position of a number in the secret code, the mark includes one - sign.
+
+  Each position in the secret code can only be matched once. For example, a guess of 1134 against a secret code of 1234 would get three plus signs: one for each of the exact matches in the first, third and fourth positions. The number match in the second position would be ignored.
+
+  Scenario Outline: submit a guess
+    Given the secret code is "<code>"
+    When I guess "<guess>"
+    Then the mark should be "<mark>"
+
+    Scenarios: no matches
+      | code | guess | mark |
+      | 1234 | 5555  |      |
+
+    Scenarios: 1 number correct
+      | code | guess | mark |
+      | 1234 | 1555  | +    |
+      | 1234 | 2555  | -    |
+
+    Scenarios: 2 numbers correct
+      | code | guess | mark |
+      | 1234 | 5254  | ++   |
+      | 1234 | 5154  | +-   |
+      | 1234 | 2545  | --   |
+
+    Scenarios: 3 numbers correct
+      | code | guess | mark |
+      | 1234 | 5234  | +++  |
+      | 1234 | 5134  | ++-  |
+      | 1234 | 5124  | +--  |
+      | 1234 | 5123  | ---  |
+
+    Scenarios: all numbers correct
+      | code | guess | mark |
+      | 1234 | 1234  | ++++ |
+      | 1234 | 1243  | ++-- |
+      | 1234 | 1423  | +--- |
+      | 1234 | 4321  | ---- |
+
+    Scenarios: matches with duplicates
+      | code | guess | mark |
+      | 1234 | 1155  | +    |
+      | 1234 | 5115  | -    |
+      | 1134 | 1155  | ++   |
+      | 1134 | 5115  | +-   |
+      | 1134 | 5511  | --   |
+      | 1134 | 1115  | ++   |
+      | 1134 | 5111  | +-   |
+      | 1155 | 1234  | +    |
+      | 1111 | 1112  | +++  |
+      | 1113 | 1121  | ++-  |
+      | 3111 | 1311  | ++-- |
+      | 3114 | 1251  | --   |
+      | 1511 | 2134  | -    |
+

code_breaker/kameda/features/step_definitions/codebreaker_steps.rb

@@ -0,0 +1,41 @@
+# -*- encoding: utf-8 -*-
+
+Given /^I am not yet playing$/ do
+end
+
+When /^I start a new game$/ do
+  game = Codebreaker::Game.new(output)
+  game.start('1234')
+end
+
+Then /^I should see "([^\"]*)"$/ do |message|
+  output.messages.should include(message)
+end
+
+Given /^the secret code is "([^\"]*)"$/ do |secret|
+  @game = Codebreaker::Game.new(output)
+  @game.start(secret)
+end
+
+When /^I guess "([^\"]*)"$/ do |guess|
+  @guess = guess
+end
+
+Then /^the mark should be "([^\"]*)"$/ do |mark|
+  @game.guess(@guess).should == mark
+end
+
+class Output
+  def messages
+    @messages ||= []
+  end
+
+  def puts(message)
+    messages << message
+  end
+end
+
+def output
+  @output ||= Output.new
+end
+

code_breaker/kameda/features/support/env.rb

@@ -0,0 +1,6 @@
+
+
+
+$LOAD_PATH << File.expand_path('../..', File.dirname(__FILE__))
+require 'codebreaker'
+