refactor(math, perfect squares): input validation and tests

Author: BrianLusina

pymath/perfect_square/README.md

@@ -7,7 +7,7 @@ Given an integer, n, return the least number of perfect square numbers that sum
 
 ## Constraints 
 
-- 1 < `n` < 10^3
+- 1 <= `n` < 10^3
 
 ## Solution
 

pymath/perfect_square/__init__.py

@@ -41,7 +41,7 @@ def num_squares(n: int) -> int:
         raise ValueError("n must be non-negative")
     if n == 0:
         return 0
-    
+
     dp = [float("inf")] * (n + 1)
     dp[0] = 0
 
@@ -62,6 +62,11 @@ def num_squares_2(n: int) -> int:
     Returns:
         int: The least number of perfect square numbers that sum to n.
     """
+    if n < 0:
+        raise ValueError("n must be non-negative")
+    if n == 0:
+        return 0
+
     # Apply reduction by removing factors of 4
     while n % 4 == 0:
         n = n // 4

pymath/perfect_square/test_perfect_squares.py

@@ -1,6 +1,6 @@
 import unittest
 from parameterized import parameterized
-from pymath.perfect_square import num_squares
+from pymath.perfect_square import num_squares, num_squares_2
 
 
 TEST_CASES = [
@@ -16,6 +16,10 @@ class NumOfPerfectSquaresTestCases(unittest.TestCase):
     @parameterized.expand(TEST_CASES)
     def test_num_of_perfect_squares(self, n: int, expected: int):
         actual = num_squares(n)
+        (self.assertEqual(expected, actual) @ parameterized.expand(TEST_CASES))
+
+    def test_num_of_perfect_squares_2(self, n: int, expected: int):
+        actual = num_squares_2(n)
         self.assertEqual(expected, actual)