Python/data_structures/linked_list/singly_linked_list.py

99 lines
2.9 KiB
Python
Raw Normal View History

2018-10-19 12:48:28 +00:00
class Node: # create a Node
def __init__(self, data):
self.data = data # given data
self.next = None # given next to None
class Linked_List:
2018-11-01 15:34:05 +00:00
def __init__(self):
self.Head = None # Initialize Head to None
2018-11-01 15:34:05 +00:00
def insert_tail(self, data):
2018-11-01 15:55:45 +00:00
if(self.Head is None): self.insert_head(data) #If this is first node, call insert_head
2018-10-19 12:48:28 +00:00
else:
2018-11-01 15:34:05 +00:00
temp = self.Head
while(temp.next != None): #traverse to last node
temp = temp.next
temp.next = Node(data) #create node & link to tail
2018-10-19 12:48:28 +00:00
2018-11-01 15:34:05 +00:00
def insert_head(self, data):
newNod = Node(data) # create a new node
if self.Head != None:
newNod.next = self.Head # link newNode to head
self.Head = newNod # make NewNode as Head
2018-10-19 12:48:28 +00:00
2018-11-01 15:34:05 +00:00
def printList(self): # print every node data
tamp = self.Head
2018-10-19 12:48:28 +00:00
while tamp is not None:
print(tamp.data)
tamp = tamp.next
2018-11-01 15:34:05 +00:00
def delete_head(self): # delete from head
temp = self.Head
if self.Head != None:
self.Head = self.Head.next
temp.next = None
return temp
2018-11-01 15:34:05 +00:00
def delete_tail(self): # delete from tail
tamp = self.Head
if self.Head != None:
if(self.Head.next is None): # if Head is the only Node in the Linked List
self.Head = None
else:
while tamp.next.next is not None: # find the 2nd last element
tamp = tamp.next
tamp.next, tamp = None, tamp.next #(2nd last element).next = None and tamp = last element
2018-11-01 15:34:05 +00:00
return tamp
2018-10-19 12:48:28 +00:00
2018-11-01 15:34:05 +00:00
def isEmpty(self):
2018-11-01 15:55:45 +00:00
return self.Head is None # Return if Head is none
2018-10-19 12:48:28 +00:00
2018-11-01 15:34:05 +00:00
def reverse(self):
2018-10-19 12:48:28 +00:00
prev = None
2018-11-01 15:34:05 +00:00
current = self.Head
2018-10-19 12:48:28 +00:00
while current:
# Store the current node's next node.
next_node = current.next
# Make the current node's next point backwards
current.next = prev
# Make the previous node be the current node
prev = current
# Make the current node the next node (to progress iteration)
current = next_node
# Return prev in order to put the head at the end
2018-11-01 15:34:05 +00:00
self.Head = prev
def main():
A = Linked_List()
2019-04-07 15:55:32 +00:00
print("Inserting 1st at Head")
a1=input()
A.insert_head(a1)
print("Inserting 2nd at Head")
a2=input()
A.insert_head(a2)
2018-11-01 15:34:05 +00:00
print("\nPrint List : ")
A.printList()
2019-04-07 15:55:32 +00:00
print("\nInserting 1st at Tail")
a3=input()
2019-04-07 15:55:32 +00:00
A.insert_tail(a3)
print("Inserting 2nd at Tail")
a4=input()
A.insert_tail(a4)
2018-11-01 15:34:05 +00:00
print("\nPrint List : ")
A.printList()
print("\nDelete Head")
A.delete_head()
print("Delete Tail")
A.delete_tail()
print("\nPrint List : ")
A.printList()
print("\nReverse Linked List")
A.reverse()
print("\nPrint List : ")
A.printList()
2018-11-01 15:34:05 +00:00
if __name__ == '__main__':
main()