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# Find pairs with given sum in doubly linked list

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

A doubly-linked list is a data structure that consists of sequentially linked nodes, and the nodes have reference to both the previous and the next nodes in the sequence of nodes.

You are given a sorted doubly linked list of size 'n', consisting of distinct positive integers, and a number 'k'.

Find out all the pairs in the doubly linked list with sum equal to 'k'.

Example :
``````Input: Linked List: 1 <-> 2 <-> 3 <-> 4 <-> 9 and 'k' = 5

Output: (1, 4) and (2, 3)

Explanation: There are 2 pairs in the linked list having sum 'k' = 5.
``````
Detailed explanation ( Input/output format, Notes, Images )

#### Sample input 1:

``````5
1 2 3 4 9
5
``````

#### Sample output 1

``````2
1 4
2 3
``````

#### Explanation for sample input 1 :

``````There are 2 pairs in the linked list having sum equal to 'k' (= 5).
``````

#### Sample input 2:

``````5
1 10 11 12 27
7
``````

#### Sample output 2:

``````0
``````

#### Explanation for sample output 2

``````There is no pair in the linked list with sum equal to 'k' (= 7).
``````

Expected time complexity :
``````The expected time complexity is O('n').
``````

Constraints:
``````2 <= 'n' <= 10 ^ 4
1 <= 'data' in any node <= 10 ^ 4
1 <= 'k' <= 10 ^ 4

'data' in every node is distinct.

Time limit: 1 second
``````
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