From f0108895c34df778810ac26995fcef7c94a998dc Mon Sep 17 00:00:00 2001
From: Margaret Finnan <msfinnan@gmail.com>
Date: Mon, 8 Apr 2019 21:15:01 -0700
Subject: [PATCH 1/3] created factorial method

---
 lib/factorial.rb | 47 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/lib/factorial.rb b/lib/factorial.rb
index 6a4a408..19a7c2e 100644
--- a/lib/factorial.rb
+++ b/lib/factorial.rb
@@ -1,6 +1,47 @@
 # Computes factorial of the input number and returns it
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n), where n is the number passed into the method. 
+# Space complexity: Constant, O(1), the only extra space used is for the variable x 
+
 def factorial(number)
-  raise NotImplementedError
+  if number == nil
+    raise ArgumentError, "Not a valid number"
+  elsif number == 0 || number == 1
+    return 1
+  else
+    x = number - 1
+    x.times do 
+      number = number * x
+      x -= 1
+    end
+    return number
+  end
 end
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+# x = number
+# while x > 1 do 
+#  x -= 1
+#  number = number *= x 
+# end 
+ 
+# return number
\ No newline at end of file

From 8a567f1ba23986f61f2cd4dfd554870685aed6d6 Mon Sep 17 00:00:00 2001
From: Margaret Finnan <msfinnan@gmail.com>
Date: Mon, 8 Apr 2019 21:17:43 -0700
Subject: [PATCH 2/3] removed commented out code from earlier attempt

---
 lib/factorial.rb | 31 +------------------------------
 1 file changed, 1 insertion(+), 30 deletions(-)

diff --git a/lib/factorial.rb b/lib/factorial.rb
index 19a7c2e..36b9d06 100644
--- a/lib/factorial.rb
+++ b/lib/factorial.rb
@@ -15,33 +15,4 @@ def factorial(number)
     end
     return number
   end
-end
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-# x = number
-# while x > 1 do 
-#  x -= 1
-#  number = number *= x 
-# end 
- 
-# return number
\ No newline at end of file
+end
\ No newline at end of file

From 577de3a9224357ec1ed5b5a9c7cdd17e8686be2c Mon Sep 17 00:00:00 2001
From: Margaret Finnan <msfinnan@gmail.com>
Date: Tue, 9 Apr 2019 20:14:59 -0700
Subject: [PATCH 3/3] worked out new method

---
 lib/factorial.rb | 66 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 51 insertions(+), 15 deletions(-)

diff --git a/lib/factorial.rb b/lib/factorial.rb
index 36b9d06..9baf1f8 100644
--- a/lib/factorial.rb
+++ b/lib/factorial.rb
@@ -1,18 +1,54 @@
 # Computes factorial of the input number and returns it
-# Time complexity: O(n), where n is the number passed into the method. 
-# Space complexity: Constant, O(1), the only extra space used is for the variable x 
+# Time complexity: Linear or O(n) where n is the number input 
+# Space complexity: Constant or O(1), will have the same  number of variables no matter the size of the input 
 
 def factorial(number)
-  if number == nil
-    raise ArgumentError, "Not a valid number"
-  elsif number == 0 || number == 1
-    return 1
-  else
-    x = number - 1
-    x.times do 
-      number = number * x
-      x -= 1
-    end
-    return number
-  end
-end
\ No newline at end of file
+return 1 if number == 0 
+if number == nil 
+  raise ArgumentError, "Enter an integer"
+end 
+a = 1
+b = number 
+while a < number
+  b = b * (number - a)
+  a += 1
+end 
+return b 
+end
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