# Recursion: Python

Recursion gives you a new perspective on problem-solving by defining a problem in terms of itself.

Start- 1
The best way to understand recursion is with lots of practice! At first, this method of solving a problem can seem unfamiliar but by the end of this lesson, we'll have implemented a variety of algo...

- 2
In the previous exercise, we used an iterative function to implement how a call stack accumulates execution contexts during recursive function calls. We'll now address the conclusion of this funct...

- 3
Now that we've built a mental model for how recursion is handled by Python, let's implement the same function and make it truly recursive. To recap: We want a function that takes an integer as an ...

- 4
Excellent job writing your first recursive function. Our next task may seem familiar so there won't be as much guidance. We'd like a function [...] that, given a positive integer as input, retu...

- 5
The previous exercise ended with a

*stack overflow*, which is a reminder that recursion has costs that iteration doesn't. We saw in the first exercise that **every recursive call spends time on th... - 6
Let's use recursion to solve another problem involving lists: [...] . We want to write a function that removes nested lists within a list

**but keeps the values contained.**[...] Remember ou... - 7
So far our recursive functions have all included a

**single**recursive call within the function definition. Let's explore a problem which pushes us to use multiple recursive calls within the fun... - 8
Data structures can also be recursive. Trees are a recursive data structure because their definition is self-referential. A tree is a data structure which contains a piece of data **and reference...

- 1
This lesson will provide a series of algorithms and an iterative or recursive implementation. Anything we write iteratively, we can also write recursively, and vice versa. Often, the difference i...

- 2
Nice work! We'll demonstrate another classic recursive function: [...] . [...] should return the [...] th Fibonacci number, where [...] is the number given as input. The first two numbers of...

- 3
Fantastic! Now we'll switch gears and show you an iterative algorithm to sum the digits of a number. This function, [...] , produces the sum of all the digits in a positive number as if they wer...

- 4
We'll use an iterative solution to the following problem: find the minimum value in a list. [...] This solution has a linear runtime, or [...] , where [...] is the number of elements in the l...

- 5
Palindromes are words which read the same forward and backward. Here's an iterative function that checks whether a given string is a palindrome: [...] Take a moment to think about the runtime of...

- 6
All programming languages you're likely to use will include arithmetic operators like [...] , [...] , and [...] . Let's pretend Python left out the multiplication, [...] , operator. How coul...

- 7
Binary trees , trees which have at most two children per node, are a useful data structure for organizing hierarchical data. It's helpful to know the depth of a tree, or how many levels make up t...

## How you'll master it

Stress-test your knowledge with quizzes that help commit syntax to memory