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# Introduction to Algorithms

## What is an algorithm?

An algorithm is a set of unambiguous, step-by-step instructions used to solve a problem. They are used by both human beings and computers.

For example, imagine you have a bag of colored blocks, and you want to find a specific block, let’s say a blue block, in the bag. Here’s a simple algorithm you can follow:

1. Take out one block from the bag.
2. Check if the block is blue.
3. If it is blue, you found the block! Yay! Stop searching.
4. If it’s not blue, put the block aside and go back to step 1.
5. Repeat steps 1-4 until you find the blue block.

In this example, the algorithm is a series of steps that helps you find the blue block. You repeat the steps until you find what you’re looking for.

Computers are really good at following algorithms, even much more complex ones. They can solve problems much faster than humans because they can follow instructions very quickly.

Algorithms for Humans

Common examples of algorithms for humans include:

Fire evacuation Procedures

Cooking Recipes

Furniture assembly instructions

Washing Machine Usage Instrucitons

## Computer Algorithms

#### Algorithms for Computers

Computers require algorithms to function and these usually come in the form of software. Computers differ from humans in that the instructions provided must completely unambiguous – they must be clear and not open to interpretation.

Click to enlarge

Computer Algorithms used in computers are usually written in text or block based programming languages such as Python or Scratch, though some algorithms are physically wired into a computer.

## Activity 1

### Write an Algorithm Activity

Choose one of the the following and write an algorithm for it:

• How to make your favourite food
• Your favourite viral Tik-tok dance
• How to make a paper plane
• How to make a cup of tea for a room full of people
• Drawing a picture of a house

## Activity 2

### Activity 2 – Alien shopping algorithm

An alien has landed on earth and you have decided to send him on an important mission – to do your weekly shopping down at the supermarket! You have been given a shopping list. The alien has never been shopping before – can you write a set of instructions for it to do the shopping for you?

Remember!

Your algorithm must be:

• Step-by-step.
• Unambiguous – Each step must be completely clear and specific.