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Programming Logic for Non-Programmers

3 Algorithms

3.1 What Are Algorithms

Most people have heard the term algorithm, especially in relation to AI or social media feeds, but what is an algorithm?

An algorithm is a set of instructions for how to do something. For AI, the term algorithm is often used as a term to represent the overall way that whatever AI that you’re working with was trained to do what it does. For social media feeds, an algorithm will determine how the platform selects which content is delivered to a user. Algorithms can be very simple or very complex.

A common analogy for an algorithm is a recipe. A recipe includes a set of ingredients, which are like the variables in your code, then lists instructions on what to do with the ingredients. But, a big difference between common recipes that you are used to seeing and an algorithm is you have to be very exact and specific when you tell a computer to do something. It isn’t enough to tell a computer, “get the data.” You have to tell it where the data is located, what format it is in, how to read it, and what format you want the data in for use in your script. So let’s do an example with a recipe on how to make cheesy mashed potatoes.

The steps are easy enough:

  1. Take potatoes and boil them until they’re done.
  2. Drain.
  3. Add butter, milk, salt/pepper to taste.
  4. Mash.
  5. Fold in cheese.
  6. Eat.

Most of us would know how to do this because we infer the instructions that are missing. But, computers aren’t intelligent like humans. They need to be explicitly told how to do something.

How many potatoes? What does boil mean? What does done mean? (which is also a question I asked my mom when reading my grandmother’s recipes.)

Computer code needs to be explicit and complete. Let’s see what that looks like with the first part of an algorithm.

Algorithm for peeling potatoes for Cheesy Mashed Potatoes

  1. Get three pounds of russet potatoes.
  2. Get bowl large enough to hold three pounds of russet potatoes.
  3. Get a vegetable peeler.
  4. Take one potato.
  5. Peel potato.
  6. Rinse potato with water.
  7. Place peeled potato in bowl
  8. Repeat 4-7 until all potatoes are washed and peeled

When you start breaking down the process into specific actions, the instructions can get quite lengthy! But this is what we need to do in order to “instruct” the computer what we want to do: splitting a large complex overall task into simple tasks that can be done one action at a time.

Essentially, that’s what computer processors do - one action at a time. Computers with multi-core processors can do multiple actions simultaneously, one action for each core. It’s just the computer is so fast, it looks like it’s doing everything at once, but it still executes commands step by step.

3.2 Breakout Activity

Timing: 15 minutes of breakout group work, followed by 10 minutes of full group discussion.

For this activity, your group will write an algorithm to make popcorn. 

“Make popcorn” is something most people have at least a general understanding of how to do (even more so than making cheesy mashed potatoes) but remember: in this scenario, your group needs to provide step-by-step directions for a computer to understand how to make popcorn.

As you write out the steps with your group, consider:

  • Are you opening a container at any point?
  • Are you making microwave popcorn, or using a stove, and does that impact the directions?
  • Is time needed to make popcorn consistent, or does this depend on other factors?
  • Is there something the computer should do if the popcorn starts burning, or other “errors” arise?