feat(day 8): implement factorial calculator with loop-based solution

Author: JohnSunny21

FreeCodeCamp/CodingQ/factorializer.py

@@ -0,0 +1,34 @@
+"""
+=======================================================================>        Factorializer       <=====================================================================
+Given an integer from zero to 20, return the factorial of that number. The factorial of a number is the product of all the numbers between 1 and the given number.
+
+The factorial of zero is 1.
+
+====================================================================================================================================================================
+O/P : ====>
+
+factorial(0) should return 1.
+"""
+
+def factorial(n):
+    fact = 1
+
+    if n < 0:
+        raise ValueError("Factorial is not defined for negative numbers")
+    if n == 0:
+        return 1
+    
+    # while n > 0:
+    #     fact *= n
+    #     n -= 1
+
+    # We can also use the for -loop here
+    for i in range(1, n+1):
+        fact *= i
+
+    return fact
+
+
+
+if __name__ == "__main__":
+    print(factorial(7))

FreeCodeCamp/CodingQ/factorializerTest.py

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+import unittest
+from factorializer import factorial
+
+class factorializerTest(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(factorial(0),1)
+
+    def test2(self):
+        self.assertEqual(factorial(5),120)
+
+    def test3(self):
+        self.assertEqual(factorial(20),2432902008176640000)
+
+
+if __name__ == "__main__":
+    unittest.main()