Python Program To Merge A Linked List Into Another Linked List At Alternate Positions
Last Updated :
17 May, 2022
Given two linked lists, insert nodes of the second list into the first list at alternate positions of the first list.
For example, if first list is 5->7->17->13->11 and second is 12->10->2->4->6, the first list should become 5->12->7->10->17->2->13->4->11->6 and second list should become empty. The nodes of the second list should only be inserted when there are positions available. For example, if the first list is 1->2->3 and the second list is 4->5->6->7->8, then the first list should become 1->4->2->5->3->6 and the second list to 7->8.
Use of extra space is not allowed (Not allowed to create additional nodes), i.e., insertion must be done in-place. The expected time complexity is O(n) where n is the number of nodes in the first list.
The idea is to run a loop while there are available positions in first loop and insert nodes of second list by changing pointers. Following are implementations of this approach.
Python3
class Node(object):
def __init__(self, data:int):
self.data = data
self.next = None
class LinkedList(object):
def __init__(self):
self.head = None
def push(self, new_data:int):
new_node = Node(new_data)
new_node.next = self.head
self.head = new_node
def printList(self):
temp = self.head
while temp != None:
print(temp.data)
temp = temp.next
def merge(self, p, q):
p_curr = p.head
q_curr = q.head
while p_curr != None and q_curr != None:
p_next = p_curr.next
q_next = q_curr.next
q_curr.next = p_next
p_curr.next = q_curr
p_curr = p_next
q_curr = q_next
q.head = q_curr
llist1 = LinkedList()
llist2 = LinkedList()
llist1.push(3)
llist1.push(2)
llist1.push(1)
llist1.push(0)
for i in range(8, 3, -1):
llist2.push(i)
print("First Linked List:")
llist1.printList()
print("Second Linked List:")
llist2.printList()
llist1.merge(p=llist1, q=llist2)
print("Modified first linked list:")
llist1.printList()
print("Modified second linked list:")
llist2.printList()
|
Output:
First Linked List:
1 2 3
Second Linked List:
4 5 6 7 8
Modified First Linked List:
1 4 2 5 3 6
Modified Second Linked List:
7 8
Time Complexity: O(N)
Auxiliary Space: O(1)
Please refer complete article on Merge a linked list into another linked list at alternate positions for more details!
Please Login to comment...