Unit 2 Notes

Recursion aims to solve a large problem by solving increasingly smaller instances of the problem.

The Droste effect is an example of recursion in art.

One of the common examples of recursion used in programming is a factorial. A factorial, written as n! is every number from n to 1 multiplied together.

For a recursive solution, it helps to think of n! as n * (n-1)! instead.

We can now make a solution in pseudocode:function factorial is: input: integer n such that n >= 1output: [n × (n-1) × (n-2) × … × 1] 1. if n is >= 1, return [ n × factorial(n-1) ] 2. otherwise, return 1 end factorial

function factorial(ByVal n as integer) if n >= 1 then return n * factorial(n-1) 'recursive call else return 1 end if end function sub main() console.writeline(factorial(10)) end sub 

RECURSION