How-To

Quick Index

Readers of Algorithms
Advantages
Steps vs Paragraph
Simple and Short
Explicit vs Implicit
Communicating Logic to Others

Readers of Algorithms

These assumptions are key to driving our approach to writing algorithms:

We assume that the "readers" of algorithms are humans (including non-programmers). This is in contrast to programming languages which are "read" (and processed) by machines.
We assume the "doer" of the algorithm knows nothing about the algorithm problem -- they are completely dependent on our steps to succeed at the task. If we tell them to turn right and there is a wall to the right, they run into the wall

Advantages

A few key advantages:

The advantage of writing algorithms (vs program code) is not getting inhibited by computer language syntax -- allowing us to focus our thoughts on solving a problem.
Humans (including non-programmers) can read algorithms
Algorithms are usually relatively straight-forward to convert to computer program code

Note that the list above tells us that algorithms have the "best of both worlds":

Understood by humans
Easily translated for machines

Steps vs Paragraph

Not This: Paragraph

We do not want to use a paragraph, story-like style. It may read okay, but it's hard for our algorithm client to know where they are.

Open a file browser and then navigate to root the directory. Then in in the file browser, right click and choose action "Create Directory" an when you receive a prompt enter name "foo" and finally hit the "Enter" key.

This: Step-by-Step

We want to go with short, simple steps.

Remember we are assuming the algorithm "user" knows nothing about the task.

The short, simple steps may be used like a "check off" list.

Numbering is optional but can be helpful -- algorithmist's choice (i.e. your choice)

Open a file browser
Navigate (in file browser) to root directory "\"
In the file browser, right click
Choose action "Create Directory"
On prompt enter name "foo"
Press "Enter" Key

Simple and Short

We want each of our steps to be simple and short.

This helps our human reader, but also remember we will be translating our algos to program code which we know is simple and short (e.g. "for", "if", "else", "while", "object.go()").

More steps is better than less. If we have "too few steps", than the reader will fail to complete the task. And "too many steps" is okay for a starting point -- the task should be successful with the only possibly improvement (later, lower priority) is tuning and optimizing.

Explicit vs Implicit

These are key words in algorithm work:

Implicit -- implied rather than expressly stated, e.g. to express or state indirectly.
Explicit -- clearly expressed; leaving nothing implied; unequivocal: explicit instructions; outspoken, precise

We want our algorithm steps to be explicit.

Implicit Example

The last step in this algo implicitly assumes that our user knows all the steps required to create a directory.

However, recall that we have assumed that our user is not at all familiar with the given task.

Open a file browser
Navigate (in file browser) to root directory "\"
Create a directory named "foo"

Explicit Example

Here we expand out the implicit step in the previous algorithm so we have the necessary explicit steps for our reader, so they can complete the task.

Open a file browser
Navigate (in file browser) to root directory "\"
In the file browser, right click
Choose action "Create Directory"
On prompt enter name "foo"
Press "Enter" Key

Communicating Logic to Others

Often in the programming field we will work with non-programmers (e.g. business team members, engineers, test team members, ...).

Algorithms can provide a good means of communicating logical ideas to non-programmers. We cannot expect them to understand a given programming languages specific syntax (that is intended for machines) but in contrast our algorithms are intended for human readers.

Algorithms (Chapter 101 - Introduction to Algorithms)

Chapter 101 - Introduction to Algorithms How-To

Contents Intro How-To Quiz Examples Recap Refs FAQs Challenge

Chapter Top Search TOC