Intro to Algorithms, Binary & Scratch

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Questions and Answers

What is the core concept of computer programming, as explained in the context?

  • Managing network communications.
  • Designing user interfaces.
  • Taking some input and creating some output to solve a problem. (correct)
  • Manipulating hardware components.

In RGB color representation, the values 72, 73, and 33 will be interpreted as black.

False (B)

What is pseudocode?

A human-readable version of code.

In Scratch, the center of the stage is at coordinate (,).

<p>0, 0</p> Signup and view all the answers

Match the big-O notation with its description:

<p>O(n) = Algorithm time increases linearly with the input size. Checking each name in a phone book one by one. O(n/2) = Algorithm time increases linearly with half the input size. Checking a phonebook two pages at a time. O(logâ‚‚n) = Algorithm time increases logarithmically with the input size. Doubling the problem only results in one more step to solve the problem.</p> Signup and view all the answers

What happens when the 'when green flag clicked' block is used in Scratch?

<p>It starts the execution of the program. (A)</p> Signup and view all the answers

In Scratch, the 'say' function only accepts string literals as input.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the 'join' function in Scratch?

<p>To combine two strings of text.</p> Signup and view all the answers

A loop simplifies code by abstracting away the ______.

<p>repetition</p> Signup and view all the answers

Match the Scratch block with its function:

<p>forever = Repeats the enclosed code indefinitely. if = Executes the enclosed code only if a certain condition is true. define = Creates a custom block (function).</p> Signup and view all the answers

What does the term 'abstraction' refer to in the context of programming?

<p>Simplifying code by removing unnecessary details. (C)</p> Signup and view all the answers

The 'define' block in Scratch allows you to create your own variables.

<p>False (B)</p> Signup and view all the answers

Explain the purpose of a conditional statement in programming.

<p>To execute code based on a condition.</p> Signup and view all the answers

In the falling trash example, the trash's initial y-position is always ______.

<p>180</p> Signup and view all the answers

Match the following terms related to binary digits:

<p>1 = Represents 'yes' or 'on' 0 = Represents 'no' or 'off'</p> Signup and view all the answers

What does ASCII stand for?

<p>American Standard Code for Information Interchange (B)</p> Signup and view all the answers

Big-O notation describes the best-case scenario for algorithm performance.

<p>False (B)</p> Signup and view all the answers

What is the Big-O notation of an algorithm that searches a phone book by checking two pages at a time?

<p>O(n/2)</p> Signup and view all the answers

The area in Scratch where you drag blocks to build a program is called the ______ area.

<p>programming</p> Signup and view all the answers

Match the Scratch block categories with their corresponding functions:

<p>Motion = Controls the movement and positioning of sprites. Looks = Determines the visual appearance of sprites, including costumes and effects. Sound = Manages audio elements, allowing sprites to play sounds.</p> Signup and view all the answers

In the context of the 'listen for keyboard' script, what is the primary function of this custom script?

<p>To control the movement of a sprite using arrow keys. (A)</p> Signup and view all the answers

The 'feel for walls' script is designed to prevent a sprite from passing through walls or boundaries.

<p>True (A)</p> Signup and view all the answers

Describe what happens when one sprite is programmed to 'follow' another sprite in Scratch.

<p>The following sprite mimics the movements of the leading sprite.</p> Signup and view all the answers

In the Yale sprite example, the sprite's movement is characterized by back and forth motions until it ______ into a wall.

<p>bumps</p> Signup and view all the answers

Match the algorithms with their corresponding Big-O notation complexity.

<p>Searching every name in a phonebook one by one = O(n) Searching 2 pages at a time = O(n/2) Doubling the problem would only result in one more step to solve the problem = O(logâ‚‚n)</p> Signup and view all the answers

In the provided Scratch code blocks for dragging trash, what is the initial y-axis position set to for the trash sprite?

<p>180 (B)</p> Signup and view all the answers

The 'ask' function in Scratch can only receive numerical input from the user.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the forever block combined with an if block that checks if the cat is touching the mouse pointer?

<p>To continuously check if the cat is touching the mouse pointer.</p> Signup and view all the answers

In the pseudocode for the AI interaction example, numerous lines of code are required to program even a ______ of possible interactions.

<p>handful</p> Signup and view all the answers

Match the purpose of the function to the example:

<p>meow = Plays the sound meow, and then waits one second. join = Combines two strings of text hello, and whatever name was provided from <code>answer</code>. say = Displays a message on the screen.</p> Signup and view all the answers

What is the primary function of the 'define' block in Scratch?

<p>To create a custom block (function). (B)</p> Signup and view all the answers

In Scratch, every program must start with the 'when green flag clicked' block.

<p>True (A)</p> Signup and view all the answers

Why is abstraction important in programming?

<p>It simplifies complex tasks by hiding unnecessary details.</p> Signup and view all the answers

In the sprite movement example, when a sprite ______ a wall, the 'feel for walls' script moves it back to a safe position.

<p>touches</p> Signup and view all the answers

Match the RGB value with the appropriate color created.

<p>72, 73, 33 = Light shade of yellow</p> Signup and view all the answers

What is the Big-O notation of an algorithm where doubling the problem only results in one more step to solve the problem?

<p>O(logâ‚‚n) (D)</p> Signup and view all the answers

The x position of the falling trash is fixed and does not change throughout the program.

<p>False (B)</p> Signup and view all the answers

In terms of the interactive 'Hello, [Name]' program, what is the input provided to the 'join' function, and what side effect does it produce?

<p>The inputs are <code>hello,</code> and <code>answer</code>, resulting in the side effect of <code>hello, [Name]</code>.</p> Signup and view all the answers

The listen for keyboard script allows you to move the sprite using the arrow keys. Each of the arrow keys on the keyboard moves the sprite around the ______.

<p>screen</p> Signup and view all the answers

Associate the RGB values with their corresponding color components:

<p>Red = Intensity of the red color component Green = Intensity of the green color component Blue = Intensity of the blue color component</p> Signup and view all the answers

Given the binary representation 01001000 01001001 00100001, what message would be received following ASCII?

<p>HI! (A)</p> Signup and view all the answers

Flashcards

Computer Programming

Transforming input into output to solve a problem.

Binary Digit Representation

A system using 0s and 1s to represent information.

ASCII

A standard for character encoding using numeric values.

RGB (Red, Green, Blue)

A color model using combinations of red, green, and blue values.

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Algorithm

A set of steps to solve a problem.

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Big-O Notation

A way to classify algorithms by how their runtime grows.

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O(n) - Linear Time

An algorithm where the time increases linearly with the input size.

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O(log n) - Logarithmic Time

An algorithm where doubling the problem only adds one step.

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Pseudocode

Human-readable version of code.

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Scratch

A visual programming language with drag-and-drop blocks.

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Scratch Stage

The area in Scratch where your program is displayed.

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String Concatenation

Combining strings together.

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Abstraction

The process of simplifying complex code by hiding details.

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Loop

A programming construct that repeats a block of code.

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Function

A reusable block of code.

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Define Block

A special block in Scratch to create custom functions.

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Conditional Statement

A statement that only runs if a condition is true.

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Forever Block

A loop that repeats indefinitely.

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Study Notes

  • Computer programming involves taking input, processing it within a "black box," and producing output, solving a problem.

Binary Representation

  • Binary digits can represent values, with each place holding a power of 2 (1, 2, 4, 8, etc.).
  • A binary representation of 72, 73, and 33 corresponds to the text "HI!" when mapped to ASCII.
  • Red, green, and blue (RGB) values, when set to 72, 73, and 33, will be read as a light shade of yellow in image readers.

Algorithms and Big-O Notation

  • Different approaches to solving a problem can be called algorithms.
  • Big-O notation describes the speed of an algorithm.
  • An algorithm that searches one by one through 100 names in a phone book has a big-O of n.
  • An algorithm that searches two pages at a time has a big-O of n/2.
  • An algorithm that halves the search space with each step has a big-O of log2n.
  • Pseudocode is a human-readable representation of code, outlining the steps of an algorithm.

Introduction to Scratch

  • Scratch has building blocks for programming, a programming area, and a stage where the program comes to life.
  • The stage in Scratch operates on a coordinate system with the center at (0, 0).
  • Dragging "when green flag clicked" and "say" blocks makes the cat sprite say "hello, world" when the green flag is clicked.
  • Providing the input "hello, world" to the "say" function results in the side effect of the cat saying "hello, world".
  • Using the "ask" function prompts the user for input, which can be stored in a variable (e.g., "answer").
  • The "join" function combines strings of text, for example, "hello" and the user's name.
  • Inputs provided to an algorithm result in outputs or side effects.

Abstraction

  • Abstraction in programming involves simplifying repetitive code by using loops or custom blocks (functions).
  • A "forever" block can be used to continuously check a condition.
  • The "define" block can create custom blocks (functions) that perform specific actions, that can also take an input to customize the blocks' actions.

Sprite Interaction

  • Sprites can be programmed to interact with the mouse, the keyboard, with walls, and others.
  • Sprites can be programmed to move around, detect when they're touching other sprites, and react accordingly.
  • The Yale sprite can be programmed to move back and forth. When it bumps into a wall, it turns around until it bumps the wall again.
  • In Scratch, sprites can be programmed to follow each other.
  • The MIT logo can be programmed to follow the Harvard sprite.

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