def find_2d_index_pt2(haystack, needle):
if type(haystack[0]) == list:
newstack = []
for stack in haystack:
newstack.extend(stack)
haystack = merge_sort(newstack)
else:
haystack = merge_sort(haystack)
print("looking for ", needle, " in haystack ", haystack)
was_found = False
def find_index_help(haystack, needle, low, high):
if high == low:
return haystack[low] == needle
mid = (low + high)//2
if haystack[mid] == needle:
print('found at', mid)
was_found = True
return was_found
elif haystack[mid] > needle:
if low == mid:
return False
else:
return find_index_help(haystack, needle, low, mid-1)
else:
return find_index_help(haystack, needle, mid+1, high)
while not was_found:
if len(haystack) == 0:
return False
else:
return find_index_help(haystack, needle, 0, len(haystack)-1)
def test_sort_is_stable(self):
"""
One of the important features of merge sort is that it is stable. This means that the pre-existing
order of equal items in the list will be preserved. This can be a desirable feature for some use-
cases. For example, it allows us to sort a list of persons by first name, and then sort it again
by last name. The result will be a list sorted by last name, then first name (when last names are
the same).
Note: to achieve this, the Person class overrides the comparison operators so we can compare using
< <= == != >= > operators, and exposes the ability to change whether this compares by first, last,
or both names via the `Person.comparison_mode` variable. This is a bit of a hack to allow us to use
our `merge_sort` function as is. For reference, Python's built-in sorting functions achieve this in
a far more elegant fashion: https://wiki.python.org/moin/HowTo/Sorting#Key_Functions
"""
names = [('Jennifer', 'Jones'), ('Jane', 'Doe'), ('Daniel', 'Smith'),
('John', 'Doe'), ('Jason', 'Jones'), ('Andrew', 'Smith'),
('David', 'Adams')]
persons = [Person(first, last) for (first, last) in names]
Person.comparison_mode = Person.ComparisonMode.FIRST_NAME
sorted_persons = merge_sort(persons)
Person.comparison_mode = Person.ComparisonMode.LAST_NAME
sorted_persons = merge_sort(sorted_persons)
expected_names = [('David', 'Adams'), ('Jane', 'Doe'), ('John', 'Doe'),
('Jason', 'Jones'), ('Jennifer', 'Jones'),
('Andrew', 'Smith'), ('Daniel', 'Smith')]
expected_persons = [
Person(first, last) for (first, last) in expected_names
]
Person.comparison_mode = Person.ComparisonMode.BOTH_NAMES
self.assertEqual(expected_persons, sorted_persons)
def test_empty(self):
self.assertEqual([], merge_sort([]))
def test_two_items(self):
self.assertEqual([1, 2], merge_sort([1, 2]))
self.assertEqual([1, 2], merge_sort([2, 1]))
self.assertEqual(['x', 'y'], merge_sort(['x', 'y']))
self.assertEqual(['x', 'y'], merge_sort(['y', 'x']))
def test_singleton(self):
self.assertEqual([1], merge_sort([1]))
self.assertEqual(['x'], merge_sort(['x']))
def test_sort_first_names(self):
self.assertEqual(['Batman', 'Harley', 'Joker', 'Robin'],
merge_sort(['Joker', 'Harley', 'Batman', 'Robin']))
def test_strs_with_characters_and_numbers(self):
self.assertEqual(['!', '3', '@', 'a', 'b', 'x'],
merge_sort(['!', '@', '3', 'a', 'b', 'x']))
self.assertEqual(['!', '#', '$', '@'],
merge_sort(['!', '@', '#', '$']))
def test_type_error_for_diff_data_types_in_list(self):
with self.assertRaises(TypeError):
merge_sort([5, 4, 3, 2, 'b'])
with self.assertRaises(TypeError):
merge_sort(['b', 2, 4, 56, 'z'])
