Big O Drills

Even or odd:- Constant Run time Complexity O(1)
Are you here?:- Nested Loop so Polynomial time Complexity O(n^2)
Doubler- Linear because values get doubled O(n)
Naive Search- Linear because if array gets doubled the algorithm will take double the amount of time to get a solution. 
               The time it takes for the algorithm to complete is dependent on the array and not item so the array can get doubled, tripled
               quadrupled in length but the time will be a linear upward slope. O(n)
Creating pairs:- Polynomial time complexity O(n^2) Has two for loops.
Computing fibonaccis:- Linear time taken will depend solely on the number parameter. O(n)
An Efficient Search:- Logorthmic Time Complexity O(logn) Time complexity is dependent on array length.
Random element:- Const Run Time Complexity O(1)
Is it prime?:- Linear becaues n can get doubled tripled etc and the time it would take for the second loop to execute will be dependent on it. O(n)