Associate Engineer

You are given the head node of a singly linked list 'head'. Your task is to modify the linked list in such a way that all the even valued nodes appear before the all odd valued node and order of nodes remain the same.

Example :-

The given singly linked list is  6 -> 5 -> 3 -> 4 -> 7 -> 1 -> 2 

The modified linked list should have all even values in starting and odd values in the end.

Ninja has been given a string 'STR' containing only lowercase alphabetic characters. Ninja has to find the number of all the different possible substrings of size two that appear in 'STR' as contiguous substrings.

For example:

If the string is “abcd”, then all possible substrings of size two are { “ab”, “bc”, “cd”}.

You are given a string ‘S’. You are also given ‘M’ integers in an array ‘A’. You perform ‘M’ operations on this string. The operations are given in an array ‘A’ of size ‘M’.

You perform the operations in the order they appear in the array ‘A’. In the ‘i’th operation, you reverse the substring of ‘S’ from the position ‘A[i]’ to ‘len(S)’ - ‘A[i]’ - 1 (0 based).

Your task is to find the string after performing all the operations.

Example :

‘S’ = “aabcd”, ‘M’ = 2, ‘A’ = [0, 1]
After 1st operation i.e, reversing from [0, 4], ‘S’ = “dcbaa”.
After 2nd operation i.e, reversing from [1, 3], ‘S’ = “dabca”.
Hence, the answer is “dabca”.

You are given a number 'N'. Your task is to find Nth prime number.

A prime number is a number greater than 1 that is not a product of two smaller natural numbers. Prime numbers have only two factors – 1 and the number itself.

Any number greater than 0 is a natural number i.e. natural numbers N = {1, 2, 3, 4,....}

For example:-

If you are asked to find the 7th prime number, it’ll be 17 because the first 7 prime numbers are 2, 3, 5, 7, 11, 13, 17.

Note: 1 is not a prime number.

Follow Up:

Try to solve the problem in O(N log log N) + O(N).

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