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Copy pathds_linked_lists.py
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292 lines (233 loc) · 7.13 KB
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class Node:
def __init__(self, value):
self.value = value
self.next = None
self.prev = None
class DLinkedList:
# Doubly Linked List
def __init__(self, value=None):
self.head = None
self.tail = None
self.length = 0
if value != None:
node = Node(value)
node.next = self.head
self.head = node
self.tail = node
self.length += 1
def prepend(self, value):
# O(1)
node = Node(value)
node.next = self.head
node.prev = None
self.head.prev = node
self.head = node
if self.tail == None:
self.tail = self.head
self.length += 1
def append(self, value):
# O(1)
node = Node(value)
node.prev = self.tail # doubly
if self.head == None:
self.head = node
self.tail = node
else:
self.tail.next = node
self.tail = node
self.length += 1
return self
def insert(self, index, value):
# O(n)
if index > self.length:
raise RangeError('index out of bounds')
if index == 0:
self.prepend(value)
return self
current_node = self.head
for i in range(index - 1):
current_node = current_node.next
node = Node(value)
node.prev = current_node
node.next = current_node.next
current_node.next = node
if node.next != None:
node.next.prev = node
self.tail = node
self.length += 1
return self
def delete(self, index):
# O(n)
if index > self.length:
raise RangeError('index out of bounds')
if index == 0:
self.head = self.head.next
self.head.prev = None
self.length -= 1
return self
delete_node = self.head
prev = None
for i in range(index):
prev = delete_node
delete_node = delete_node.next
if index == self.length - 1:
self.tail = prev
self.tail.next = None
else:
prev.next = delete_node.next
if delete_node.next != None:
delete_node.next.prev = prev
self.length -= 1
return self
def print_list(self):
# O(n)
current = self.head
while current != None:
print(current.value)
current = current.next
def print_list_reverse(self):
# O(n)
current = self.tail
while current != None:
print(current.value)
current = current.prev
def search(self, value):
# O(n)
current = self.head
while current != None:
if current.value == value:
return True
current = current.next
return False
class SLinkedList:
def __init__(self, value=None):
self.head = None
self.tail = None
self.length = 0
if value != None:
node = Node(value)
node.next = self.head
self.head = node
self.tail = node
self.length += 1
def prepend(self, value):
# O(1)
node = Node(value)
node.next = self.head
self.head = node
if self.tail == None:
self.tail = self.head
self.length += 1
def append(self, value):
# O(1)
node = Node(value)
if self.head == None:
self.head = node
self.tail = node
else:
self.tail.next = node
self.tail = node
self.length += 1
return self
def insert(self, index, value):
# O(n)
if index > self.length:
raise RangeError('index out of bounds')
if index == 0:
self.prepend(value)
return self
current_node = self.head
for i in range(index - 1):
current_node = current_node.next
node = Node(value)
node.next = current_node.next
current_node.next = node
self.tail = node
self.length += 1
return self
def delete(self, index):
# O(n)
if index > self.length:
raise RangeError('index out of bounds')
if index == 0:
self.head = self.head.next
self.head.prev = None
self.length -= 1
return self
delete_node = self.head
prev = None
for i in range(index):
prev = delete_node
delete_node = delete_node.next
if index == self.length - 1:
self.tail = prev
self.tail.next = None
else:
prev.next = delete_node.next
self.length -= 1
return self
def print_list(self):
current = self.head
while current != None:
print(current.value)
current = current.next
def reverse(self):
# O(n)
prev = None
current = self.head
for i in range(self.length):
temp = current.next
current.next = prev
prev = current
current = temp
self.head = prev
return self
def search(self, value):
# O(n)
current = self.head
while current != None:
if current.value == value:
return True
current = current.next
return False
def main():
'''
apples
8293 ---> grapes
3232 --> pears
372 --> null
'''
obj1 = {"a" : True}
obj2 = obj1
#print(obj1, obj2)
#print(obj1 is obj2)
#print(obj1 == obj2)
#print(id(obj1), id(obj2))
obj2 = None # new memory location
a = 2
b = 2
# a and b point to the same object of 2 from different variable memory locations
b = 3
b = a # b now has the same variable memory location as a
a = 2 # b is 2
b = 3 # b is 3, a is 2
#print(a,b)
linked_list = SLinkedList(3)
linked_list.prepend(2)
linked_list.prepend(1)
#linked_list.insert(0,0)
#linked_list.append(6)
#linked_list.insert(4,4)
#linked_list.insert(5,5)
#linked_list.insert(7,7)
#linked_list.delete(0)
#linked_list.delete(6)
#linked_list.delete(4)
#print(linked_list.search(4))
#print(linked_list.search(0))
linked_list.print_list()
linked_list.reverse()
print("--")
linked_list.print_list()
if __name__ == "__main__":
main()