From e770e8875797ecab2a43b6b1ef7004c32f36166d Mon Sep 17 00:00:00 2001
From: Ken Ding <ken.ding@mail.com>
Date: Tue, 27 Jun 2017 02:41:11 +0930
Subject: [PATCH] finish assignment 1

---
 Gemfile           |  2 +-
 Gemfile.lock      | 29 +++++++++++++++++++++++++++++
 lib/ruby_intro.rb | 28 +++++++++++++++++++++-------
 3 files changed, 51 insertions(+), 8 deletions(-)
 create mode 100644 Gemfile.lock

diff --git a/Gemfile b/Gemfile
index 2a4bda74..38d40a5d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,4 @@
 source 'https://rubygems.org'
-ruby '2.3'
+ruby '2.3.3'
 
 gem 'rspec'
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 00000000..705df4df
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,29 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    diff-lcs (1.3)
+    rspec (3.5.0)
+      rspec-core (~> 3.5.0)
+      rspec-expectations (~> 3.5.0)
+      rspec-mocks (~> 3.5.0)
+    rspec-core (3.5.4)
+      rspec-support (~> 3.5.0)
+    rspec-expectations (3.5.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.5.0)
+    rspec-mocks (3.5.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.5.0)
+    rspec-support (3.5.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  rspec
+
+RUBY VERSION
+   ruby 2.3.3p222
+
+BUNDLED WITH
+   1.14.6
diff --git a/lib/ruby_intro.rb b/lib/ruby_intro.rb
index e74c4c28..9fdd1c90 100644
--- a/lib/ruby_intro.rb
+++ b/lib/ruby_intro.rb
@@ -3,33 +3,47 @@
 # Part 1
 
 def sum arr
-  # YOUR CODE HERE
+  arr.inject(0, :+)
 end
 
 def max_2_sum arr
-  # YOUR CODE HERE
+  sum(arr.sort {|x, y| y <=> x}.take(2))
 end
 
 def sum_to_n? arr, n
-  # YOUR CODE HERE
+  return false if arr.size < 2
+
+  arr.permutation(2).any? {|a, b| a + b == n}
 end
 
 # Part 2
 
 def hello(name)
-  # YOUR CODE HERE
+  "Hello, #{name}"
 end
 
 def starts_with_consonant? s
-  # YOUR CODE HERE
+  /^[b-df-hj-np-tv-z]/i.match(s) != nil
 end
 
 def binary_multiple_of_4? s
-  # YOUR CODE HERE
+  return true if s == "0"
+  /^[10]*00$/.match(s) != nil
 end
 
 # Part 3
 
 class BookInStock
-# YOUR CODE HERE
+  attr_accessor :isbn, :price
+
+  def initialize isbn, price
+    raise ArgumentError if isbn.empty? || price <= 0
+
+    @isbn = isbn
+    @price = price
+  end
+
+  def price_as_string
+    sprintf("$%2.2f", @price)
+  end
 end