Recursion Review

- Recursion is a programming concept that allows you to call a function repeatedly until a base case is reached. Here is an example of a recursive function that calculates the factorial of a number: ```py def find_factorial(n): if n == 0: return 1 return n * find_factorial(n - 1) ``` In the above example, the `find_factorial` function is called recursively until `n` reaches `0`. When `n` is `0`, the base case is reached and the function returns `1`. The function then returns the product of `n` and the result of the recursive call to `find_factorial(n - 1)`. - Recursion allows you to handle something with an unknown depth, such as deeply nested dictionaries and lists, or a file tree. - A call stack is used to keep track of the function calls in a recursive function. Each time a function is called, it is added to the call stack. When the base case is reached, the function calls are removed from the stack. - You should carefully define the base case. Otherwise, the function can keep calling itself until Python raises a `RecursionError`. - Recursion is useful for solving mathematical problems such as factorial and Fibonacci, traversing trees and graphs, and generating permutations and combinations.