SDE - Intern

You have been given an integer array/list(ARR) of size 'N'. It only contains 0s, 1s and 2s. Write a solution to sort this array/list.

Note :

Try to solve the problem in 'Single Scan'. ' Single Scan' refers to iterating over the array/list just once or to put it in other words, you will be visiting each element in the array/list just once.

You are given an integer N, and you need to find the number of Special Primes smaller than or equal to N.

Note:

1. A Prime number is a number that has only two factors 1 and N itself.
2. A Prime number P is known as Special Prime if it can 
be represented as follows:
    P = A^2 + B^4
where A and B are positive integers.
3. A and B should be greater than 0.

You have been given a column title as appears in an Excel sheet, return its corresponding column number.

For example:

A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28 
...