From aa41865856d086ceda975f85aa6ecec75253b386 Mon Sep 17 00:00:00 2001
From: jpg-130 <jigsgandhi97@gmail.com>
Date: Sat, 29 Jun 2019 15:51:54 +0530
Subject: [PATCH 1/3] adding factorial

---
 dynamic_programming/factorial.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 dynamic_programming/factorial.py

diff --git a/dynamic_programming/factorial.py b/dynamic_programming/factorial.py
new file mode 100644
index 000000000000..61c33e24f480
--- /dev/null
+++ b/dynamic_programming/factorial.py
@@ -0,0 +1,19 @@
+#Factorial of a number using memoization
+def factorial(num):
+    if num<0:
+        return -1
+    if result[num]!=-1:
+        return result[num]
+    else:
+        result[num]=num*factorial(num-1)
+        #uncomment the following to see how recalculations are avoided
+        #print(result)
+        return result[num]
+
+#factorial of num
+result=[-1]*10
+result[0]=result[1]=1
+print(factorial(5))
+#uncomment the following to see how recalculations are avoided
+# print(factorial(3))
+# print(factorial(7))
\ No newline at end of file

From 1011db440b6a14c62b519691699489e2fb29bfc6 Mon Sep 17 00:00:00 2001
From: Jigyasa G <33327397+jpg-130@users.noreply.github.com>
Date: Sun, 14 Jul 2019 15:02:05 +0530
Subject: [PATCH 2/3] adding doctest

---
 dynamic_programming/factorial.py | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/dynamic_programming/factorial.py b/dynamic_programming/factorial.py
index 61c33e24f480..c2119adcf1f1 100644
--- a/dynamic_programming/factorial.py
+++ b/dynamic_programming/factorial.py
@@ -1,7 +1,16 @@
 #Factorial of a number using memoization
 def factorial(num):
+    """
+    >>> factorial(7)
+    5040
+    >>> factorial(-1)
+    'Number should not be negative.'
+    >>> [factorial(i) for i in range(5)]
+    [1, 1, 2, 6, 24]
+    """
+    
     if num<0:
-        return -1
+        return "Number should not be negative."
     if result[num]!=-1:
         return result[num]
     else:
@@ -11,9 +20,16 @@ def factorial(num):
         return result[num]
 
 #factorial of num
-result=[-1]*10
-result[0]=result[1]=1
-print(factorial(5))
 #uncomment the following to see how recalculations are avoided
+##result=[-1]*10
+##result[0]=result[1]=1
+##print(factorial(5))
 # print(factorial(3))
-# print(factorial(7))
\ No newline at end of file
+# print(factorial(7))
+
+
+if __name__ == "__main__":
+    import doctest
+    result=[-1]*10
+    result[0]=result[1]=1
+    doctest.testmod()

From ba98234d31a01a360b66d6de1b28fa0b423c1422 Mon Sep 17 00:00:00 2001
From: Jigyasa G <33327397+jpg-130@users.noreply.github.com>
Date: Wed, 17 Jul 2019 11:36:02 +0530
Subject: [PATCH 3/3] Update factorial.py

---
 dynamic_programming/factorial.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/dynamic_programming/factorial.py b/dynamic_programming/factorial.py
index c2119adcf1f1..7c6541ee2a74 100644
--- a/dynamic_programming/factorial.py
+++ b/dynamic_programming/factorial.py
@@ -1,4 +1,6 @@
 #Factorial of a number using memoization
+result=[-1]*10
+result[0]=result[1]=1
 def factorial(num):
     """
     >>> factorial(7)
@@ -27,9 +29,6 @@ def factorial(num):
 # print(factorial(3))
 # print(factorial(7))
 
-
 if __name__ == "__main__":
     import doctest
-    result=[-1]*10
-    result[0]=result[1]=1
     doctest.testmod()