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# Introduction To Doubly Linked List

Easy
0/40
Average time to solve is 10m
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## Problem statement

You are given an array ‘Arr’ of size ‘N’ consisting of positive integers.

Here, the head of the doubly linked list is the first element of the array, and the tail of the doubly linked list is the last element.

Note:
``````A doubly linked list is one in which it is possible to access the next and the previous nodes from a node in the linked list (if they exist).
``````

Example:
``````Input: ‘N’ = 4, ‘Arr’ = [4, 2, 5, 1]

Output: 4 2 5 1

Explanation: Doubly Linked List for the array ‘Arr’ = [4, 2, 5, 1] is 4 <-> 2 <-> 5 <-> 1.
``````

Detailed explanation ( Input/output format, Notes, Images )
Sample Input 1:
``````4
4 2 5 1
``````
Sample Output 1 :
``````4 2 5 1
``````
Explanation Of Sample Input 1:
``````Input: ‘N’ = 4, ‘Arr’ = [4, 2, 5, 1]

Output: 4 2 5 1

Explanation:
Doubly Linked List for the array ‘Arr’ = [4, 2, 5, 1] is 4 <-> 2 <-> 5 <-> 1.
``````
Sample Input 2:
``````5
4 3 2 1 5
``````
Sample Output 2:
``````4 3 2 1 5
``````
Explanation Of Sample Input 2:
``````Input: ‘N’ = 5, ‘Arr’ = [4, 3, 2, 1, 5]

Output: 4 3 2 1 5

Explanation:
Doubly Linked List for the array ‘Arr’ = [4, 3, 2, 1, 5] is 4 <-> 3 <-> 2 <-> 1 <-> 5.
``````

Expected Time Complexity:
``````Try solving this in O(N).
``````

Constraints:
``````1 <= 'N' <= 10^4
1 <= 'Arr[i]' <= 10^5

Time Limit: 1 sec
``````
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