feat(day 9): add sumOfSquares function with optimal mathematical formula

Author: JohnSunny21

FreeCodeCamp/CodingQ/sumOfSquares.py

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+"""
+================================================================>       Sum of Squares       <====================================================================================
+Given a positive integer up to 1,000, return the sum of all the integers squared from 1 up to the number.
+
+==========================================================================================================================================================================================
+O/P : ====>
+
+1. sum_of_squares(5) should return 55.
+2. sum_of_squares(10) should return 385.
+3. sum_of_squares(25) should return 5525.
+
+"""
+
+def sum_of_squares(n):
+    return sum(num**2 for num in range(1,n+1))
+
+
+# Bonus : Which is a Mathematical Formula
+# If we optimize the code further, the sum of squares from 1 to n can be computed directly:
+# sum = n(n+1)(2n + 1) // 6
+
+def sum_of_squares_optimal(n):
+    return n * (n + 1) * (2 * n + 1) // 6
+# This avoids iteration entirely and is lighting -fast especially usefull if n gets very large.
+
+
+if __name__ == "__main__":
+    print(sum_of_squares(5))

FreeCodeCamp/CodingQ/sumOfSquaresTest.py

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+import unittest
+from sumOfSquares import sum_of_squares
+
+class sumOfSquares(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(sum_of_squares(5),55)
+
+    def test2(self):
+        self.assertEqual(sum_of_squares(10),385)
+
+    def test3(self):
+        self.assertEqual(sum_of_squares(25),5525)
+
+    def test4(self):
+        self.assertEqual(sum_of_squares(500),41791750)
+
+    def test5(self):
+        self.assertEqual(sum_of_squares(1000),333833500)
+
+
+if __name__ == "__main__":
+    unittest.main()