# Program to find linked list intersection from two linked list in Python

Suppose we have two sorted linked lists L1 and L2, we have to make a new sorted linked list which contains the intersection of these two lists.

So, if the input is like L1 = [2, 4, 8] L2 = [3, 4, 8, 10], then the output will be [4, 8, ]

To solve this, we will follow these steps −

• head := a new node with value 0
• cur := head
• while l1 and l2 are not empty, do
• if value of l1 < value of l2, then
• l1 := next of l1
• otherwise when value of l2 < value of l1, then
• l2 := next of l2
• otherwise,
• next of cur := a new node with value same as value of l1
• l1 := next of l1
• l2 := next of l2
• cur := next of cur
• return next of head

Let us see the following implementation to get better understanding −

## Example

Live Demo

class ListNode:
def __init__(self, data, next = None):
self.val = data
self.next = next
def make_list(elements):
for element in elements[1:]:
while ptr.next:
ptr = ptr.next
ptr.next = ListNode(element)
print('[', end = "")
while ptr:
print(ptr.val, end = ", ")
ptr = ptr.next
print(']')
class Solution:
def solve(self, l1, l2):
head = cur = ListNode(0)
while l1 and l2:
if l1.val < l2.val:
l1 = l1.next
elif l2.val < l1.val:
l2 = l2.next
else:
cur.next = ListNode(l1.val)
l1 = l1.next
l2 = l2.next
cur = cur.next
ob = Solution()
L1 = make_list([2, 4, 8])
L2 = make_list([3, 4, 8, 10])
print_list(ob.solve(L1, L2))

## Input

[2, 4, 8], [3, 4, 8, 10]

## Output

[4, 8, ]

Updated on: 19-Nov-2020

148 Views

##### Kickstart Your Career

Get certified by completing the course