#optimization
6 problems

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

Find the missing element in a randomized range of numbers
I take n consecutive integers, toss one of them out and mix up the remaining n1 integers as completely unsorted. Find the missing integer.

Is the given String a repeated subpattern?
Given a string, return whether it is made of a perfectly repeated string pattern.

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

Graph Cycle Detection
You have a directed connected graph. Write an algorithm that detects any cycle, if one exists, and returns a list of its nodes.

Find the middle node of a Linked List
Given a Singly Linked List, write an algorithm to find the middle node. You may not use more than one loop of any kind.