52 lines
1.1 KiB
Python
52 lines
1.1 KiB
Python
|
# reverse a given linkedlist
|
||
|
|
|
||
|
|
class Node:
|
||
|
|
# Constructor to initialize the node object
|
||
|
|
def __init__(self, data=0, next=None):
|
||
|
|
self.data = data
|
||
|
|
self.next = next
|
||
|
|
|
||
|
|
|
||
|
|
class LinkedList:
|
||
|
|
# Constructor to initialize head
|
||
|
|
def __init__(self) -> None:
|
||
|
|
self.head = None
|
||
|
|
|
||
|
|
# Function to insert a new node at the beginning
|
||
|
|
def push(self, data):
|
||
|
|
node = Node(data)
|
||
|
|
node.next = self.head
|
||
|
|
self.head = node
|
||
|
|
|
||
|
|
# Function to print the list from beginning
|
||
|
|
def printList(self):
|
||
|
|
temp = self.head
|
||
|
|
while temp:
|
||
|
|
print(temp.data, end=" ")
|
||
|
|
temp = temp.next
|
||
|
|
|
||
|
|
# Function to reverse the list
|
||
|
|
def reverse(self):
|
||
|
|
dummy = None
|
||
|
|
cur = self.head
|
||
|
|
while cur:
|
||
|
|
nextTemp = cur.next
|
||
|
|
cur.next = dummy
|
||
|
|
dummy = cur
|
||
|
|
cur = nextTemp
|
||
|
|
self.head = dummy
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == '__main__':
|
||
|
|
ll = LinkedList()
|
||
|
|
ll.push(1)
|
||
|
|
ll.push(2)
|
||
|
|
ll.push(3)
|
||
|
|
ll.push(4)
|
||
|
|
ll.push(5)
|
||
|
|
print("Before Reverse")
|
||
|
|
ll.printList()
|
||
|
|
ll.reverse() # reversing
|
||
|
|
print("\nAfter Reversing")
|
||
|
|
ll.printList()
|