O(1): Constant-no loops
O(log N)：Logarithmic- usually searching algorithms have log n if they are sorted (Binary Search)
O(n)：Linear- for loops, while loops through n items
O(n log(n))：Log Liniear- usually sorting operations
O(n^2)：Quadratic- every element in a collection needs to be compared to ever other element. Two
nested loops
O(2^n)：Exponential- recursive algorithms that solves a problem of size N
O(n!)：Factorial- you are adding a loop for every element
Rule 1: Always worst Case
Rule 2: Remove Constants
Rule 3: Different inputs should have different variables.
Rule 4: Drop Non-dominant terms
