The examples presented below should help you get a feel for when you should choose recursion. Typically, the readability of the code will be the biggest determining factor.

In some cases, using recursion may result in slower execution time.

Recursive implementations often consume more memory than non-recursive ones.

For some problems, a recursive solution, though possible, will be awkward rather than elegant.

On the other hand, recursion isn’t for every situation. An example of this appears later in this tutorial. A non-recursive algorithm to walk through a nested structure is likely to be somewhat clunky, while a recursive solution will be relatively elegant. Because these are nested structures, they readily fit a recursive definition. Traversal of tree-like data structures is another good example. If you were devising an algorithm to handle such a case programmatically, a recursive solution would likely be cleaner and more concise. However, some situations particularly lend themselves to a self-referential definition-for example, the definition of ancestors shown above. So, strictly speaking, recursion usually isn’t necessary.

Most programming problems are solvable without recursion. It refers to a coding technique in which a function calls itself. In programming, recursion has a very precise meaning. Notice how the concept that is being defined, ancestors, shows up in its own definition. For example, suppose you wanted to describe the set of people that make up your ancestors. Self-referential situations often crop up in real life, even if they aren’t immediately recognizable as such.

The Free Dictionary: A method of defining a sequence of objects, such as an expression, function, or set, where some number of initial objects are given and each successive object is defined in terms of the preceding objectsĪ recursive definition is one in which the defined term appears in the definition itself.

Wiktionary: The act of defining an object (usually a function) in terms of that object itself.

: The act or process of returning or running back.

Here are some online definitions of recursion: The word recursion comes from the Latin word recurrere, meaning to run or hasten back, return, revert, or recur. Free Bonus: Get a sample chapter from Python Basics: A Practical Introduction to Python 3 to see how you can go from beginner to intermediate in Python with a complete curriculum, up to date for Python 3.9.

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