From bcf0bfd0143b50b2f3da5fdd8f228ff4d6a07cbf Mon Sep 17 00:00:00 2001
From: laneia <laneiamurray@gmail.com>
Date: Wed, 19 Jun 2019 15:20:19 -0700
Subject: [PATCH 1/2] one line solution with .inject

---
 lib/fibonacci.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/fibonacci.rb b/lib/fibonacci.rb
index 606755b..b330c14 100644
--- a/lib/fibonacci.rb
+++ b/lib/fibonacci.rb
@@ -5,8 +5,9 @@
 # ....
 # e.g. 6th fibonacci number is 8
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) because creating an array of n elements, constant array[0] look up time
+# Space complexity: O(n) because creating an array of n elements
+
 def fibonacci(n)
-  raise NotImplementedError
+  (0..n).inject([1, 0]) { |(a, b), _| [b, a + b] }[0]
 end

From 98799e91ec0bf9636405dd6de9ec2ee8e39a7528 Mon Sep 17 00:00:00 2001
From: laneia <laneiamurray@gmail.com>
Date: Wed, 19 Jun 2019 15:33:44 -0700
Subject: [PATCH 2/2] added in commented out recursive solution

---
 lib/fibonacci.rb | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/fibonacci.rb b/lib/fibonacci.rb
index b330c14..10f87ba 100644
--- a/lib/fibonacci.rb
+++ b/lib/fibonacci.rb
@@ -11,3 +11,10 @@
 def fibonacci(n)
   (0..n).inject([1, 0]) { |(a, b), _| [b, a + b] }[0]
 end
+
+# With recursion
+# def fibonacci(n)
+#   raise ArgumentError if !n || n < 0
+#   return n if n < 2
+#   return (fibonacci(n - 1) + fibonacci(n - 2))
+# end