Return the Nth element of the Fibonacci series (1, 1, 2, 3, 5, 8, 13, 21, ...) efficiently without using any FOR or WHILE loops.

Then calculate the average time complexity of inserting n new items into an empty brand new ArrayList.

Find the contiguous 2-dimensional sub-matrix with the maximum sum, in a given 2 dimensional matrix of n elements of signed integer type.

You are given n, a positive integer. Return true if n is a prime number, and false if it's not.