From 3c04d3c5cec3b6ed8764455d655280bf10783db3 Mon Sep 17 00:00:00 2001
From: Angela <angela.ohh@gmail.com>
Date: Sun, 21 Apr 2019 15:09:13 -0700
Subject: [PATCH 1/2] recursive solution

---
 lib/fibonacci.rb        | 45 ++++++++++++++++++++++++++++++++++++++++-
 specs/fibonacci_spec.rb | 11 +++++-----
 2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/lib/fibonacci.rb b/lib/fibonacci.rb
index 606755b..bd0f2bc 100644
--- a/lib/fibonacci.rb
+++ b/lib/fibonacci.rb
@@ -7,6 +7,49 @@
 
 # Time complexity: ?
 # Space complexity: ?
+def fibonacci_non_recursion(n)
+  # n i step nth fibonacci number in series
+  # if n = 5
+  # 0 1 1 2 3
+  # set first_num = 0
+  # set second_num = 1
+  # set count of number to be 3
+  # until the count is greater than the input n
+  # new number is equal to first_num + second_num
+  # reassign first_num and second_num
+
+  if n.class != Integer || n < 0
+    raise ArgumentError, "Your input #{n} is not an non-negative integer!"
+  end
+
+  first_num = 0
+  second_num = 1
+  fibonacci_num = 0
+  count = 2
+
+  if n == 0
+    return fibonacci_num
+  elsif n == 1
+    return fibonacci_num + 1
+  else
+    until count > n
+      fibonacci_num = first_num + second_num
+      first_num = second_num
+      second_num = fibonacci_num
+      count += 1
+    end
+  end
+  return fibonacci_num
+end
+
 def fibonacci(n)
-  raise NotImplementedError
+  if n.class != Integer || n < 0
+    raise ArgumentError, "Your input #{n} is not an non-negative integer!"
+  end
+
+  if n < 2
+    return n
+  else
+    return fibonacci(n - 1) + fibonacci(n - 2)
+  end
 end
diff --git a/specs/fibonacci_spec.rb b/specs/fibonacci_spec.rb
index f518644..604e0fa 100644
--- a/specs/fibonacci_spec.rb
+++ b/specs/fibonacci_spec.rb
@@ -1,6 +1,7 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
-require_relative '../lib/fibonacci'
+require "minitest/autorun"
+require "minitest/reporters"
+require "minitest/pride"
+require_relative "../lib/fibonacci"
 
 describe "fibonacci" do
   describe "basic tests" do
@@ -29,11 +30,11 @@
   describe "edge cases" do
     # if the parameter is an object, check for nil
     it "nil object is not an integer" do
-      proc {fibonacci(nil)}.must_raise ArgumentError
+      proc { fibonacci(nil) }.must_raise ArgumentError
     end
 
     it "negative input" do
-      proc {fibonacci(-9)}.must_raise ArgumentError
+      proc { fibonacci(-9) }.must_raise ArgumentError
     end
 
     it "zero input" do

From 458b8c11c273642180a02fb280ce86805c1fe7a0 Mon Sep 17 00:00:00 2001
From: Angela <angela.ohh@gmail.com>
Date: Sun, 21 Apr 2019 15:10:49 -0700
Subject: [PATCH 2/2] added time/space complexity

---
 lib/fibonacci.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/fibonacci.rb b/lib/fibonacci.rb
index bd0f2bc..526c3f2 100644
--- a/lib/fibonacci.rb
+++ b/lib/fibonacci.rb
@@ -5,8 +5,8 @@
 # ....
 # e.g. 6th fibonacci number is 8
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) where n is size of input
+# Space complexity: O(1)
 def fibonacci_non_recursion(n)
   # n i step nth fibonacci number in series
   # if n = 5