Data Structures, Algorithms, And Big O Notation! A Beginners Guide.

I may or may not regret this decision, but I’m sticking to it.

Data Structures, what are they?

  • Array: data is organized within brackets in sequential order. Each data entry within these brackets is called an element and is separated by a comma. These elements can be accessed via numbered indexes which start at 0 and increment per data entry. A Javascript example would be:
below is an example of how to extract a value from this array
> catchPhrase[0]
  • Hash: data is organized within braces with a key pointing to a value. These key/value pairs are generally separated by a coma. The data (value) can be accessed by its key. This has the advantage of having a constant reference point to access said value. The syntax for this varies in different languages, and in Javascript this is called an object. Here’s a Javascript example:
below is an example of how to extract a value from this hash
> characters['Android']
A visual aid for different data structures, these can even be nested inside one another.

What is an Algorithm?

  1. Be a Bruce Wayne esq. billionaire.
  2. Either go to giant robot building school or hire someone who has.
  3. Buy required tools and materials.
  4. Assemble Gundam Wing style robot or hire someone to do so.
below are some examples of different returns this function might have, this function uses the previously defined catchPhrase array by default.
> findIndexOfElement("Showtime!")
> findIndexOfElement("Not Present")

A Brief Description Of Big O Notation

Sadly this has absolutely nothing to do with Big O Notation, but I’m stubbornly keeping this analogy.
  • Constant Time or O(1) the algorithm has a constant run time relative to its input. Generally this is something that can be done in one “step”
  • Linear Time or O(n) the algorithms execution time increases relative to the size of its input. Generally this is some basic iteration
  • Quadratic Time or O(n²) the algorithms execution time increases relative to the size of its input squared. Generally this involves looped iteration
As you can imagine the runtime for this increases exponentially as the input increases because you are iterating through the entire array per element.





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