class Stack:
def __init__(self):
self.ll = LinkedList()
def push(self, data):
self.ll.prepend(data)
def pop(self):
data = self.ll.head.value
self.ll.delete(0)
return data
class Stack:
"""
Stack implementation using linked list which
supports max operation.
Implemented using two linked lists. One for elements
themselfs and one for current max value.
Time complexity: O(1)
Space complexity: O(N) + O(N) for max value.
"""
def __init__(self):
self._main_stack = LinkedList()
self._max_stack = LinkedList()
self._map = {}
def peek(self):
"""
Takes object from the top of this stack
without removing it from the stack.
"""
return self._main_stack.head.value
def pop(self):
"""
Removes object from the top of this stack
and returns that object.
"""
head = self._main_stack.head.value
self._main_stack.delete(0)
self._max_stack.delete(0)
return head
def push(self, item):
"""
Pushes an item onto the top of this stack.
"""
if not self._max_stack.head or self._max_stack.head.value < item:
self._max_stack.prepend(item)
else:
self._max_stack.prepend(self._max_stack.head.value)
self._main_stack.prepend(item)
def max(self):
return self._max_stack.head.value
def test_delete(self):
ll = LinkedList()
ll.append(1)
ll.append(2)
ll.append(3)
ll.append(4)
ll.delete(0)
self.assertEqual([2, 3, 4], ll.to_list())
ll.delete(1)
self.assertEqual([2, 4], ll.to_list())
ll.delete(1)
self.assertEqual([2], ll.to_list())
ll.delete(0)
self.assertEqual([], ll.to_list())
class LinkedListTest(unittest.TestCase):
def setUp(self):
self.ll = LinkedList()
def tearDown(self):
self.ll = None
pass
def test_insert(self):
self.ll.insert(5)
self.assertEqual(self.ll.toList(), [5])
self.assertNotEqual(self.ll.toList(), [6])
self.ll.insert(10)
self.assertEqual(self.ll.toList(), [5, 10])
def test_insert_after(self):
self.ll.insert(5)
self.ll.insert(10)
self.ll.insert_after(6, 7)
self.assertEqual(self.ll.toList(), [5, 7, 10])
self.ll.insert_after(100, 1000)
self.assertEqual(self.ll.toList(), [5, 7, 10, 1000])
def test_delete(self):
self.ll.insert(5)
self.ll.delete(5)
self.assertEqual(self.ll.toList(), [])
self.ll.insert(10)
self.ll.insert(100)
self.ll.insert(1000)
self.ll.delete(100)
self.assertEqual(self.ll.toList(), [10, 1000])
self.ll.delete(1000)
self.assertEqual(self.ll.toList(), [10])
self.ll.delete(10)
self.assertEqual(self.ll.toList(), [])
self.ll.delete(100)
self.assertEqual(self.ll.toList(), [])
def test_delete_at(self):
self.ll.delete_at(0)
self.assertEqual(len(self.ll), 0)
self.ll.insert(5)
self.ll.delete_at(0)
self.assertEqual(len(self.ll), 0)
self.ll.push(10)
self.ll.push(100)
self.ll.push(1000)
self.ll.delete_at(2)
self.assertEqual(self.ll.toList(), [1000, 100])
def test_length(self):
self.assertEqual(len(self.ll), 0)
self.ll.insert(5)
self.assertEqual(len(self.ll), 1)
self.ll.insert(5)
self.assertEqual(len(self.ll), 2)
self.ll.insert(10)
self.ll.insert(100)
self.ll.insert(1000)
self.ll.delete(100)
self.assertEqual(len(self.ll), 4)
def test_contains(self):
self.assertFalse(5 in self.ll)
self.ll.insert(5)
self.assertTrue(5 in self.ll)
self.ll.push(0)
self.assertTrue(0 in self.ll)
self.assertFalse(3 in self.ll)
def test_push(self):
self.ll.push(5)
self.assertEqual(self.ll.toList(), [5])
self.ll.push(10)
self.assertEqual(self.ll.toList(), [10, 5])
def test_pop(self):
self.ll.push(5)
self.assertEqual(self.ll.pop(), 5)
self.assertEqual(self.ll.toList(), [])
self.ll.push(1)
self.ll.push(2)
self.ll.push(3)
self.ll.push(4)
self.ll.push(100)
self.assertEqual(self.ll.pop(), 100)
self.assertEqual(self.ll.toList(), [4, 3, 2, 1])
def test_swap_at(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.ll.swap_at(1, 3)
self.assertEqual(self.ll.toList(), [1, 4, 3, 2, 5])
self.ll.swap_at(0, 4)
self.assertEqual(self.ll.toList(), [5, 4, 3, 2, 1])
self.ll.swap_at(0, 1)
self.assertEqual(self.ll.toList(), [4, 5, 3, 2, 1])
self.ll.swap_at(4, 3)
self.assertEqual(self.ll.toList(), [4, 5, 3, 1, 2])
def test_kth(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.assertEqual(self.ll.kth(0), 1)
self.assertEqual(self.ll.kth(3), 4)
def test_last_kth(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.assertEqual(self.ll.last_kth(1), 5)
self.assertEqual(self.ll.last_kth(3), 3)
def test_count(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(5)
self.ll.push(1)
self.assertEqual(self.ll.count(1), 1)
self.assertEqual(self.ll.count(5), 2)
def test_reverse(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.ll.reverse()
self.assertEqual(self.ll.toList(), [5, 4, 3, 2, 1])
class LinkedListTest(unittest.TestCase):
def setUp(self):
self.ll = LinkedList()
def tearDown(self):
self.ll = None
pass
def test_insert(self):
self.ll.insert(5)
self.assertEqual(self.ll.toList(), [5])
self.assertNotEqual(self.ll.toList(), [6])
self.ll.insert(10)
self.assertEqual(self.ll.toList(), [5, 10])
def test_insert_after(self):
self.ll.insert(5)
self.ll.insert(10)
self.ll.insert_after(6, 7)
self.assertEqual(self.ll.toList(), [5, 7, 10])
self.ll.insert_after(100, 1000)
self.assertEqual(self.ll.toList(), [5, 7, 10, 1000])
def test_delete(self):
self.ll.insert(5)
self.ll.delete(5)
self.assertEqual(self.ll.toList(), [])
self.ll.insert(10)
self.ll.insert(100)
self.ll.insert(1000)
self.ll.delete(100)
self.assertEqual(self.ll.toList(), [10, 1000])
self.ll.delete(1000)
self.assertEqual(self.ll.toList(), [10])
self.ll.delete(10)
self.assertEqual(self.ll.toList(), [])
self.ll.delete(100)
self.assertEqual(self.ll.toList(), [])
def test_delete_at(self):
self.ll.delete_at(0)
self.assertEqual(len(self.ll), 0)
self.ll.insert(5)
self.ll.delete_at(0)
self.assertEqual(len(self.ll), 0)
self.ll.push(10)
self.ll.push(100)
self.ll.push(1000)
self.ll.delete_at(2)
self.assertEqual(self.ll.toList(), [1000,100])
def test_length(self):
self.assertEqual(len(self.ll), 0)
self.ll.insert(5)
self.assertEqual(len(self.ll), 1)
self.ll.insert(5)
self.assertEqual(len(self.ll), 2)
self.ll.insert(10)
self.ll.insert(100)
self.ll.insert(1000)
self.ll.delete(100)
self.assertEqual(len(self.ll), 4)
def test_contains(self):
self.assertFalse(5 in self.ll)
self.ll.insert(5)
self.assertTrue(5 in self.ll)
self.ll.push(0)
self.assertTrue(0 in self.ll)
self.assertFalse(3 in self.ll)
def test_push(self):
self.ll.push(5)
self.assertEqual(self.ll.toList(), [5])
self.ll.push(10)
self.assertEqual(self.ll.toList(), [10, 5])
def test_pop(self):
self.ll.push(5)
self.assertEqual(self.ll.pop(), 5)
self.assertEqual(self.ll.toList(), [])
self.ll.push(1)
self.ll.push(2)
self.ll.push(3)
self.ll.push(4)
self.ll.push(100)
self.assertEqual(self.ll.pop(), 100)
self.assertEqual(self.ll.toList(), [4, 3, 2, 1])
def test_swap_at(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.ll.swap_at(1, 3)
self.assertEqual(self.ll.toList(), [1, 4, 3, 2, 5])
self.ll.swap_at(0, 4)
self.assertEqual(self.ll.toList(), [5, 4, 3, 2, 1])
self.ll.swap_at(0, 1)
self.assertEqual(self.ll.toList(), [4, 5, 3, 2, 1])
self.ll.swap_at(4, 3)
self.assertEqual(self.ll.toList(), [4, 5, 3, 1, 2])
def test_kth(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.assertEqual(self.ll.kth(0), 1)
self.assertEqual(self.ll.kth(3), 4)
def test_last_kth(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.assertEqual(self.ll.last_kth(1), 5)
self.assertEqual(self.ll.last_kth(3), 3)
def test_count(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(5)
self.ll.push(1)
self.assertEqual(self.ll.count(1), 1)
self.assertEqual(self.ll.count(5), 2)
def test_reverse(self):
self.ll.push(5)
self.ll.push(4)
self.ll.push(3)
self.ll.push(2)
self.ll.push(1)
self.ll.reverse()
self.assertEqual(self.ll.toList(), [5, 4, 3, 2, 1])
