Problem of the day
We have a linked list 1->2->3->4->5->6->7 and so on. You are supposed to swap pairs of a linked list like swap (1,2), (3,4), (5,6), and so on.
1. You may not modify the data in the list’s nodes; only nodes themselves may be changed. Because imagine a case where a node contains many fields, so there will be too much unnecessary swap.
2. If a pair of a node does not exist, then leave the node as it is.
The input contains the elements of the singly linked list separated by a single space and terminated by -1. Hence, -1 would never be a list element.
For each input, print a single line containing the same number of integers as in the list, in swapped order.
You do not need to print anything, it has already been taken care of just implement the given function.
0 <= N <= 5 * 10 ^ 5
-10 ^ 9 <= DATA <= 10 ^ 9 and DATA != -1
Where ‘N’ is the length of the linked list and 'DATA' is data in each node.
Time limit: 1 sec.
11 21 13 14 15 -1
21 11 14 13 15 -1
Swap 11 with 21 then swap 13 with 14 and 15 has no pair so leave that node as it is.
-13 14 -21 18 -20 30 -1
14 -13 18 -21 30 -20 -1
Swap -13 with 14 then swap -21 with 18 and then swap -20 to with 30.