Insertion In Doubly Linked List

Easy

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Average time to solve is 15m

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Problem statement

You are given a Doubly linked list, where every node in the linked list contains two pointers ‘next’ and ‘prev’ which point to the next node and previous node in the list respectively. All nodes have some positive integer value associated with them. Your task is to insert an integer value ‘VAL’ in the linked list at a given position ‘K’.

Note:

The position given will always be less than or equal to the length of the linked list.
Assume that the Indexing for the linked list starts from 0.

EXAMPLE:

Input :
‘K’ = 3, ‘VAL’ = 4
list = [1, 2, 3]
Output: [1, 2, 3, 4]

The ‘VAL’ = 4, is inserted at end of the above doubly linked list.

Detailed explanation ( Input/output format, Notes, Images )

Input Format :

The first line will contain the integer 'T', the number of test cases.

The first line of each test case contains the integers ‘K’, and ‘VAL’, denoting the position of insertion operation, and the value of the new node to be inserted in the list respectively.

The second line of each test case contains an array of positive integers denoting the nodes of the linked list.

Output format :

For each test case, print the doubly linked list after the insertion operation.

Note :

You don't need to print anything. It has already been taken care of. Just implement the given function.
Here, '-1' marks the end of the linked list.

Constraints :

1 <= 'T' <= 10
1 <= Length of the list <= 10^4
0 <= ‘K’ <= Length of the list, where ‘K’ is 0-indexed.
1 <= 'VAL' <= 10^5

Time Limit: 1 sec

Sample Input 1:

2
0 0
1 2 3 4 -1
5 5
5 4 3 2 1 -1

Sample Outpu.t 1:

0 1 2 3 4
5 4 3 2 1 5

Explanation Of Sample Input 1 :

For the first test case, ‘K’ = 0 denotes the starting index of the list, so the new element is inserted before the head of the list and the new head will be then a node with ‘VAL’ = 0

Hence, the resulting doubly linked list would be : 0 1 2 3 4

For the second test case, ‘K’ = 5 = size of the list denotes the new element to be inserted at the end of the list. 

Hence, the resulting doubly linked list would be: 5 4 3 2 1 5

Sample Input 2 :

Sample Output 2 :

10 11 4 5
2 5 8

Console