Factorial

Factorial, often denoted as n!, is a mathematical operation. In the context of computer science and algorithm complexity, it represents an extremely high growth rate. This occurs because of the way a factorial is calculated: The product of all positive integers less than or equal to a non-negative integer n. Thus, if an algorithm has a complexity of O(n!), it means the running time increases factorially based on the size of the input data set. That is, for an input of size n, the algorithm does n * (n-1) * (n-2) * ... * 1 operations. O(n!) is essentially the worst case scenario of complexity for an algorithm and is seen in brute-force search algorithms, such as the traveling salesman problem via brute-force.