4 Steps to design a Recursive function quicker

Recursion has been a form of abstraction of the problem to be solved instead of relying only in iteration especially looping structures. Some of its drawbacks detail it as not very efficient in computer resource management for program executions, which also affects the speed of the program flow. More especially to programmers, they are commonly considered as a complicated technique to master or derive in coding together in its formulation and simulation.

So we can say that recursion is still an essential technique at least to be above other basic skill set in programming, although it could be tough as again that it is tricky to apply recursion without even aid or a clue to design one by even a fair programmer. This is not always the option for relying from sources as other guys who advice "just google it!!" but then "because you're noob haha!". Being serious to recursion is the usual reason for taking hours or days to design at least a simple recursive function. But this is the right attitude for a professional programmer. Therefore, these steps shall relieve you in strategizing to design recursion in code and get in-depth with the logic of recursion.

Well then, let’s begin harnessing your recursive skills to design a recursive function that should take least of 30 minutes only.

1. Think recursively

The obvious path and also the crucial step for recursion. To develop this kind of mindset could be tedious when exploring a problem that is devised in recursion. But as you practice exploring and developing recursive solutions, you begin to explore the logical process that fits recursion with the problem environment. For this step, it is advised that you read upon this related article "How to think in Recursion for programming?" and later get back in here. To glimpse the interesting content about this article, here are the titles of the steps:

1. Analyze the behavior of solving the problem naturally
2. Simpler, smaller versions of the problem
3. Establish required base cases
4. Structure general case
5. Backtrack successive versions of the problem

These additional steps are essential for thinking recursively and get to know better the fundamentals of recursion in programming. This relies on a sample problem about factorials and follows though the next steps below.

2. Layout draft of recursive algorithm (optional)

To flatten and blueprint your recursive idea, you can turn this by formulating two types of recursive procedures: Recursive definition and Recurring relation. We first demonstrate recursive definition by relying from the sample. We can outline it with the single base case and the single statement of general case for the problem of factorial.

Recursive definition

The figure above shows the equation formulated that serves the blueprint. n! is the recursive problem that outlines its cases that follow. Top always align with the base case following the condition that answers the recurring problem n! if n equals 0. When the base case value failed to meet its condition, below case is evaluated next. This will bring out n x (n-1)! to answer n!.

Recurrence relation also works same as recursive definition but is sort of direct equation to lay out the recursion algorithm.

Recurrence relation

Although it’s much mathematical than recursive definition, it’s easier to outline the recursive algorithm by the general case first then define the base case. In the figure, f is the function that holds parameter in subscript. The base case directly defines the parameter to return a specific value.

By then, these recursive procedure types are not limited and may differ for other problems (including math problems) that may require recursion and can only be applicable to this planning with custom or hybrid approach like applying pseudocode. This step just allows the problem solution from recursion to be easily implemented from just the equation rather pieces of scattered ideas or concepts from your thoughts.

3. Evaluate resources to use

In programming, resource handling from a system is essential to developing a program as it defines its quality. Unfortunately, function calls lead to new memory allocations for its respective parameters and local variables, when to an extent may bloat your system. This is especially in Java and exemptions from other languages.

To design an efficient recursive function:

• Place local variables just before the leading statements that will use it. Instances are that these variables are simply just declared and initialized, yet are not used as the program flow met a statement or condition that lead to terminate the function without even getting to use the variables.
• Use minimal variables if possible. You use the value directly for process if it is not referred more than once by other statements.
• Try simplifying other statements. Some code statements contain algorithms that are redundant or wasteful in processing values so generalize it for efficiency.

4. Test recursive function

Finally, you can then test your recursive function for debugging and observations. This is the step to check if it suppresses infinite recursions or continuous call to the recursive function, gives out right results, and is robust enough, where all are tested from a set of inputs or test suites. Present bugs can be fixed by reviewing the recursive definition, manually simulating the function, or adding another base case to filter the input parameter.

As of then, hope you have gone through these hefty yet helpful steps. To recap, here is a summary of what you have learned.

• Think recursively in terms of the problem nature, versions of the problem, cases that build the recursion, and tracing back recursive calls.
• Layout the idea as a recursive definition by formulating a standard equation as the blueprint.
• Design the recursive function in terms of efficiency by proper resource handling.
• Test the recursive function for errors and accuracy.

This article about recursion is loosely based from the book ‘Java Programming: From Problem Analysis to Program Design’ by D.S. Malik. You can head over this link to Amazon to buy the book or look from your local bookstores and learn about Java.

In your opinion, what are some programming examples that are truly adapted for recursion?