def test_add_at_tail(self):
dll = Dll()
dll.add_at_head("apple")
dll.add_at_head("orange")
dll.add_at_tail("mango")
assert str(dll.head) == "orange"
assert dll.size_dll() == 3
def test_add_at_nth_position(self):
dll = Dll()
dll.add_at_head(1)
dll.add_at_head(2)
dll.add_at_head(3)
dll.add_at_head(4)
dll.add_at_nth_position(5, 0)
size = dll.size_dll()
assert size == 5
def test_size(self):
dll = Dll()
size = dll.size_dll()
# Test an empty Linked List
assert size == 0
# Test Linked List with some nodes
dll.add_at_head(1)
dll.add_at_head(2)
dll.add_at_head(3)
dll.add_at_head(4)
size = dll.size_dll()
assert size == 4
def test_add_at_head(self):
dll = Dll()
dll.add_at_head("apple")
dll.add_at_head("orange")
assert str(dll.head) == "orange"
def test_is_empty(self):
dll = Dll()
assert dll.is_empty() is True
node = DllNode(1)
dll.head = node
assert dll.is_empty() is False
# Reverse doubly linked list
from doublylinkedlist.doubly_linkedlist import Dll
def reverse_dll(current):
"""Reverse a linked list using recursion."""
if current.next is None:
dll.head = current
return dll.head
reverse_dll(current.next)
temp = current.next
temp.next = current
current.next = None
if __name__ == "__main__":
dll = Dll()
dll.add_at_head(1)
dll.add_at_head(3)
dll.add_at_head(5)
dll.add_at_head(7)
print("Elements of linked list:")
dll.print_dll()
print("Head:")
print(dll.head)
print("Elements of reversed linked list:")
reverse_dll(dll.head)
dll.print_dll()
print("Head after reversing:")
print(dll.head)
def printReverse(current):
"""Print all the elements of the list in reverse."""
temp = current
if current is None:
return
# Traverse to the end
while current.next:
current = current.next
# Traverse backward
while current:
print(current.data)
current = current.prev
if __name__ == "__main__":
dll = Dll()
dll.add_at_head(1)
dll.add_at_head(3)
dll.add_at_tail(5)
dll.add_at_tail(7)
print("Head of linked list:")
print(dll.head)
print("Forward:")
printForward(dll.head)
print("Reverse:")
printReverse(dll.head)
current.prev = None
current = None
return
# case 4:
else:
prev_node = current.prev
prev_node.next = None
current.prev = None
current = None
return
current = current.next
if __name__ == "__main__":
dll = Dll()
dll.add_at_tail(1)
dll.add_at_tail(2)
dll.add_at_tail(3)
dll.add_at_tail(2)
dll.add_at_tail(1)
dll.add_at_tail(4)
dll.add_at_tail(2)
dll.add_at_tail(1)
print("List: ")
dll.print_dll()
print("\n")
print("List after removing duplicates: ")
remove_duplicates(dll.head)
dll.print_dll()
def print_forward(current):
"""Print all the elements of the linked list using recursion."""
if current is None:
return "Exit the linked list."
print(current.data)
print_forward(current.next)
def print_reverse(current):
"""Print all the elements of the linked list after reversing using recursion."""
if current is None:
return "Exit the linked list."
print_reverse(current.next)
print(current.data)
if __name__ == "__main__":
dll = Dll()
dll.add_at_head(1)
dll.add_at_head(3)
dll.add_at_head(5)
dll.add_at_head(7)
print("Elements of linked list:")
print_forward(dll.head)
print("Head of linked list:")
print(dll.head)
print("Elements of reversed linked list:")
print_reverse(dll.head)
print("Head of linked list:")
print(dll.head)