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Intersection of Linked Lists

Difficulty: EASY
Contributed By
Anish De |Level 1
Avg. time to solve
20 min
Success Rate
70%

Problem Statement

You are given two linked lists L1 and L2 which are sorted in ascending order. You have to make a linked list with the elements which are present in both the linked lists and are present in ascending order.

Example:-
L1 = 1->2->3->4->7
L2 = 2->4->6->7

ANSWER:- The answer should be 2->4->7 because 2,4, and 7 are present in both the linked lists.
Input Format :
The first line contains a single integer ‘T’ representing the number of test cases. Then each test case follows.

The first line of every test case contains the nodes of the first linked list. The line ends with -1 to indicate that the linked list is over.

The next line of every test case contains the head of the second linked list. The line ends with -1 to indicate that the linked list is over.
Output Format :
For each test case, return the head of the intersecting linked list. If the intersecting linked list is empty, return NULL (denoted by -1).

The output of each test case should be printed in a separate line.
Note :
You are not required to print anything, it has already been taken care of. Just implement the function.    
Constraints :
1 <= T <= 5
1 <= Length of the the two linked lists <= 10^5 

Time Limit = 1 sec
Sample Input 1 :
2
1 3 5 -1
1 2 4 -1
2 3 -1
2 3 4 -1
Sample Output 1 :
1 -1
2 3 -1
Explanation for Sample Output 1 :
In the first test case, the intersecting linked list is 1, so the node containing 1 is returned.

In the second test case, the intersecting linked list is 2->3, so the node containing 2 is returned.
Sample Input 2 :
1
2 3 4 -1
1 5 6 -1
Sample Output 2 :
-1 
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