Palindrome products: sync expected test results and input data with p…

…roblem-specifications. (#1814)

exercises/palindrome-products/example.py

@@ -3,12 +3,12 @@
 from math import log10, floor, ceil
 
 
-def largest_palindrome(max_factor, min_factor):
+def largest(min_factor, max_factor):
     return get_extreme_palindrome_with_factors(max_factor, min_factor,
                                                "largest")
 
 
-def smallest_palindrome(max_factor, min_factor):
+def smallest(max_factor, min_factor):
     return get_extreme_palindrome_with_factors(max_factor, min_factor,
                                                "smallest")
 
@@ -17,37 +17,36 @@ def get_extreme_palindrome_with_factors(max_factor, min_factor, extreme):
     palindromes_found = palindromes(max_factor, min_factor,
                                     reverse=(extreme == "largest"))
     factor_pairs = None
-    for palin in palindromes_found:
-        factor_pairs = ((fact, palin // fact)
-                        for fact in range(min_factor, max_factor + 1)
-                        if palin % fact == 0)
+    for palindrome in palindromes_found:
+        factor_pairs = ((factor, palindrome // factor)
+                        for factor in range(min_factor, max_factor + 1)
+                        if palindrome % factor == 0)
         factor_pairs = list(pair for pair in factor_pairs
                             if min_factor <= pair[1] <= max_factor)
         if len(factor_pairs) > 0:
             break
 
-    if factor_pairs is None or len(factor_pairs) == 0:
+    if not factor_pairs:
         return (None, [])
 
-    return (palin, factor_pairs)
+    return (palindrome, factor_pairs)
 
 
-def reverse_num(n):
-    rev = 0
-    while n > 0:
-        rev *= 10
-        rev += (n % 10)
-        n //= 10
-    return rev
+def reverse_num(number):
+    reversed = 0
+    while number > 0:
+        reversed *= 10
+        reversed += (number % 10)
+        number //= 10
+    return reversed
 
 
-def num_digits(n):
-    return int(floor(log10(n) + 1))
+def num_digits(number):
+    return int(floor(log10(number) + 1))
 
 
 def palindromes(max_factor, min_factor, reverse=False):
     """Generates all palindromes between `min_factor`**2 and max_factor`**2
-
     If `reverse` is True, will produce the palindromes in decreasing order,
     from `max_factor`**2 down to `min_factor`**2. This is needed for
     `largest_palindrome`, since it won't have to iterate through a
@@ -62,55 +61,55 @@ def palindromes(max_factor, min_factor, reverse=False):
     minimum = min_factor ** 2
     maximum = max_factor ** 2
 
-    def gen_palins_of_length(nd, reverse=reverse):
+    def gen_palindromes_of_length(num_digits, reverse=reverse):
         """Generates all palindromes with `nd` number of digits that are
         within the desired range.
-
         Again, if `reverse` is True, the palindromes are generated in
         reverse order.
         """
-        even_nd = (nd % 2 == 0)
+        even_nd = (num_digits % 2 == 0)
 
-        min_left_half = max(10 ** (int(ceil(nd / 2)) - 1),
-                            minimum // (10 ** (nd // 2)))
-        max_left_half = min((10 ** int(ceil(nd / 2))) - 1,
-                            maximum // (10 ** (nd // 2)))
+        min_left_half = max(10 ** (int(ceil(num_digits / 2)) - 1),
+                            minimum // (10 ** (num_digits // 2)))
+        max_left_half = min((10 ** int(ceil(num_digits / 2))) - 1,
+                            maximum // (10 ** (num_digits // 2)))
 
         current_left_half = min_left_half if not reverse else max_left_half
 
         def make_palindrome(left_half, even_nd=False):
             right_half = (reverse_num(left_half)
                           if even_nd
                           else reverse_num(left_half // 10))
-            return (left_half * (10 ** (nd // 2))) + right_half
+            return (left_half * (10 ** (num_digits // 2))) + right_half
 
         if not reverse:
             while current_left_half <= max_left_half:
-                palin = make_palindrome(current_left_half, even_nd)
-                if minimum <= palin <= maximum:
-                    yield palin
-                elif palin > maximum:
+                palindrome = make_palindrome(current_left_half, even_nd)
+                if minimum <= palindrome <= maximum:
+                    yield palindrome
+                elif palindrome > maximum:
                     # since palindromes are generated in increasing order,
                     #   we break out of the loop once we've exceeded the
                     #   maximum value
                     break
                 current_left_half += 1
         else:
             while current_left_half >= min_left_half:
-                palin = make_palindrome(current_left_half, even_nd)
-                if minimum <= palin <= maximum:
-                    yield palin
-                elif palin < minimum:
+                palindrome = make_palindrome(current_left_half, even_nd)
+                if minimum <= palindrome <= maximum:
+                    yield palindrome
+                elif palindrome < minimum:
                     # since palindromes are generated in decreasing order,
                     #   we break out of the loop once we've gone below the
                     #   minimum value
                     break
                 current_left_half -= 1
 
-    min_nd, max_nd = num_digits(minimum), num_digits(maximum)
+    min_nd = num_digits(minimum)
+    max_nd = num_digits(maximum)
 
     lengths = (range(min_nd, max_nd + 1)
                if not reverse
                else range(max_nd, min_nd - 1, -1))
 
-    return chain(*map(gen_palins_of_length, lengths))
+    return chain(*map(gen_palindromes_of_length, lengths))

exercises/palindrome-products/palindrome_products.py

@@ -1,6 +1,6 @@
-def largest_palindrome(max_factor, min_factor):
+def largest(min_factor, max_factor):
     pass
 
 
-def smallest_palindrome(max_factor, min_factor):
+def smallest(min_factor, max_factor):
     pass

exercises/palindrome-products/palindrome_products_test.py

@@ -1,6 +1,6 @@
 """
-Notes regarding the implementation of smallest_palindrome and
-largest_palindrome:
+Notes regarding the implementation of smallest and
+largest:
 
 Both functions must take two keyword arguments:
     max_factor -- int
@@ -13,70 +13,69 @@
 
 import unittest
 
-from palindrome_products import smallest_palindrome, largest_palindrome
+from palindrome_products import smallest, largest
 
 
 # Tests adapted from `problem-specifications//canonical-data.json` @ v1.2.0
 
 class PalindromeProductsTest(unittest.TestCase):
     def test_smallest_palindrome_from_single_digit_factors(self):
-        value, factors = smallest_palindrome(min_factor=1, max_factor=9)
+        value, factors = smallest(min_factor=1, max_factor=9)
         self.assertEqual(value, 1)
-        self.assertFactorsEqual(factors, {(1, 1)})
+        self.assertFactorsEqual(factors, [[1, 1]])
 
     def test_largest_palindrome_from_single_digit_factors(self):
-        value, factors = largest_palindrome(min_factor=1, max_factor=9)
+        value, factors = largest(min_factor=1, max_factor=9)
         self.assertEqual(value, 9)
-        self.assertFactorsEqual(factors, {(1, 9), (3, 3)})
+        self.assertFactorsEqual(factors, [[1, 9], [3, 3]])
 
     def test_smallest_palindrome_from_double_digit_factors(self):
-        value, factors = smallest_palindrome(min_factor=10, max_factor=99)
+        value, factors = smallest(min_factor=10, max_factor=99)
         self.assertEqual(value, 121)
-        self.assertFactorsEqual(factors, {(11, 11)})
+        self.assertFactorsEqual(factors, [[11, 11]])
 
     def test_largest_palindrome_from_double_digit_factors(self):
-        value, factors = largest_palindrome(min_factor=10, max_factor=99)
+        value, factors = largest(min_factor=10, max_factor=99)
         self.assertEqual(value, 9009)
-        self.assertFactorsEqual(factors, {(91, 99)})
+        self.assertFactorsEqual(factors, [[91, 99]])
 
     def test_smallest_palindrome_from_triple_digit_factors(self):
-        value, factors = smallest_palindrome(min_factor=100, max_factor=999)
+        value, factors = smallest(min_factor=100, max_factor=999)
         self.assertEqual(value, 10201)
-        self.assertFactorsEqual(factors, {(101, 101)})
+        self.assertFactorsEqual(factors, [[101, 101]])
 
     def test_largest_palindrome_from_triple_digit_factors(self):
-        value, factors = largest_palindrome(min_factor=100, max_factor=999)
+        value, factors = largest(min_factor=100, max_factor=999)
         self.assertEqual(value, 906609)
-        self.assertFactorsEqual(factors, {(913, 993)})
+        self.assertFactorsEqual(factors, [[913, 993]])
 
     def test_smallest_palindrome_from_four_digit_factors(self):
-        value, factors = smallest_palindrome(min_factor=1000, max_factor=9999)
+        value, factors = smallest(min_factor=1000, max_factor=9999)
         self.assertEqual(value, 1002001)
-        self.assertFactorsEqual(factors, {(1001, 1001)})
+        self.assertFactorsEqual(factors, [[1001, 1001]])
 
     def test_largest_palindrome_from_four_digit_factors(self):
-        value, factors = largest_palindrome(min_factor=1000, max_factor=9999)
+        value, factors = largest(min_factor=1000, max_factor=9999)
         self.assertEqual(value, 99000099)
-        self.assertFactorsEqual(factors, {(9901, 9999)})
+        self.assertFactorsEqual(factors, [[9901, 9999]])
 
     def test_empty_for_smallest_palindrome_if_none_in_range(self):
-        value, factors = smallest_palindrome(min_factor=1002, max_factor=1003)
+        value, factors = smallest(min_factor=1002, max_factor=1003)
         self.assertIsNone(value)
         self.assertFactorsEqual(factors, [])
 
     def test_empty_for_largest_palindrome_if_none_in_range(self):
-        value, factors = largest_palindrome(min_factor=15, max_factor=15)
+        value, factors = largest(min_factor=15, max_factor=15)
         self.assertIsNone(value)
         self.assertFactorsEqual(factors, [])
 
-    def test_error_for_smallest_if_min_is_more_than_max(self):
+    def test_error_for_smallest_palindrome_if_min_is_more_than_max(self):
         with self.assertRaisesWithMessage(ValueError):
-            value, factors = smallest_palindrome(min_factor=10000,
-                                                 max_factor=1)
+            value, factors = smallest(min_factor=10000, max_factor=1)
 
-    def test_error_for_largest_if_min_is_more_than_max(self):
+    def test_error_for_largest_palindrome_if_min_is_more_than_max(self):
         with self.assertRaisesWithMessage(ValueError):
-            value, factors = largest_palindrome(min_factor=2, max_factor=1)
+            value, factors = largest(min_factor=2, max_factor=1)
 
     # Utility functions
     def setUp(self):