Shulou(Shulou.com)06/02 Report--

This article mainly explains "the collation of recursive knowledge points in Python". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "the collation of recursive knowledge points in Python".

Recursive recursion

Recursion is a way to solve problems.

The core of recursion: decompose the problem into smaller identical problems and continue to decompose them until the problem is small enough to be solved in a very simple way

Recursive direction: "decompose the problem into the same problem on a smaller scale"

Recursive end condition "until the problem is small enough to be solved in a very simple way"

Recursive characteristics: call yourself in the algorithm flow

An example of recursion: summation of sequences

Problem description: given a list, return the sum of all numbers

Conventional solution: using for cycle

01

Instead of using for while loops, to take advantage of recursion, you need to break down the problem into smaller and smaller directions.

The summation of the list is essentially the addition of two numbers, so the summation of the scale of the list is divided into the superposition of two fixed operands.

For example: calculation [1, 3, 5, 7, 9]

Observing the example, it is found that the list summation has a repetitive pattern, and the problem can be summarized into a formula: the sum of the sequence = "the first number" + "the sum of the rest".

Another conclusion can be drawn from the example:

"the sum of the remainder", which is where recursive calls are made, is getting smaller and smaller.

When there is only one number left, it is the end condition of the recursion, which is returned directly.

Recursive solution:

01

Recursion actually implements the loop in another way. In the analysis, you can directly regard the place where the recursive call is called as a loop. In debug, the program flow is the same as the loop.

Recursion in sequence summation algorithm: "Sum problem of shorter sequence"

Recursive summary

Three laws of recursion:

There must be a basic end condition (recursive to only one minimum problem)

Recursion must change the state and evolve to the basic end condition (reducing the size of the problem)

The recursive algorithm must call itself (solve the same problem that reduces the size)

At this point, I believe that you have a deeper understanding of "the collation of recursive knowledge points in Python". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.