Given a linked list, swap every two adjacent nodes and return its head.
Example 1:
1 2 3 4
>> 2 1 4 3
Example 2:
2 4 6 3 1 5
>> 4 2 3 6 5 1
Input contains a list of elements in a linked list and the expected output can be achieved by using a single linked list.
Firstly a class called Node is created, which represents a node of linked list with
variables next that acts as a pointer and data used to store elements in it.
The method rearrange is used to swap the adjacent nodes in following manner :
# A linked list node
class Node:
def __init__(self, data=None, next=None):
self.data = data
self.next = next
# Helper function to print given linked list
def printList(head):
ptr = head
while ptr:
print(ptr.data, end=" ")
ptr = ptr.next
print("")
# Function to pairwise swap adjacent nodes of a linked list
def rearrange(head):
# if list is empty or contains just one node
if head is None or head.next is None:
return head
curr = head
prev = None
# consider two nodes at a time and swap their links
while curr and curr.next:
temp = curr.next
curr.next = temp.next
temp.next = curr
if prev is None:
head = temp
else:
prev.next = temp
prev = curr
curr = curr.next
return head
if __name__ == '__main__':
head = None
a = list(map(int, input().split()))
for i in reversed(a):
head = Node(i, head)
head = rearrange(head)
printList(head)