Study Notes: AP CSP Control Structures

Pseudocode (AP Style)

Loops and Random

Iteration: For loops

Overview

  • For loops are specific types of iteration that repeat code blocks a fixed number of times.

Pseudocode Syntax

  • Structure:

    • REPEAT n TIMES
      {

      }

  • The block of statements within the for loop executes exactly n times.

Example in Pseudocode

  • The following pseudocode initializes a sum variable and computes the sum of numbers from 0 to 4:

    • Pseudocode:
      sum ← 0
      count ← 0
      repeat 5 times {
      sum ← sum + count
      count ← count + 1
      }
      DISPLAY(count)

Python Example

  • Python Code:

sum = 0
for i in range(5):
    sum += i
print(sum)

  • This code initializes a variable sum, iterates 5 times adding the loop variable to sum, and finally prints the sum.

Iteration: While Loops

Overview

  • While loops continue to execute the block of statements as long as the provided Boolean expression evaluates to true.

Pseudocode Syntax

  • Structure:

    • REPEAT UNTIL (condition)
      {

      }

Example in Pseudocode

  • The following pseudocode initializes num and decreases it until it is less than zero:

    • Pseudocode:
      num ← 5
      repeat until num < 0 {
      print(num)
      num ← num - 1
      }
      OUTPUT 5 4 3 2 1 0

Python Example

  • Python Code:

num = 5
while num >= 0:
    print(num)
    num = num - 1

  • This code initializes a numeric variable and prints it until it is negative, demonstrating a countdown.

Comparison of Programs A and B

Program A Analysis

  • Code Structure:

REPEAT UNTIL (i > 10)
    DISPLAY i
    i ← i + 1

  • Output Values:
    Program A displays the values: 1 2 3 4 5 6 7 8 9 10.

Program B Analysis

  • Code Structure:

REPEAT UNTIL (i > 10)
    i ← i + 1
    DISPLAY i

  • Output Values:
    Program B also displays the values: 1 2 3 4 5 6 7 8 9 10.
    Both programs display the same sequence of numbers despite the difference in their structure.

Random: Coin Flip Game

Game Description

  • Players flip a fair coin three times. The winning condition is that all flips must result in the same outcome (either all heads or all tails).
    If this is achieved, the player wins; otherwise, they lose.

Pseudocode for Coin Flip Game

flip ← RANDOM(0,3)
IF (flip = 3):
    DISPLAY "You win!"
ELSE:
    DISPLAY "You lose."
sum ← 0
REPEAT 3 TIMES:
    sum ← sum + RANDOM(0,1)
IF (sum = 3):
    DISPLAY "You win!"
ELSE:
    DISPLAY "You lose."

Random: Spinner

Spinner Probability Example

  • The probability of the spinner landing on different colors is illustrated as follows:

  • For a single color (Pink):

    • Pseudocode Example:
      ```pseudocode
      spin ← RANDOM(1,6)
      if spin = 1:
      DISPLAY("Pink")
      else:
      DISPLAY("Not Pink")

- For another color (Green):
  - **Pseudocode Example:** 
    ```pseudocode
spin ← RANDOM(1,6)
if spin = 1 or spin = 2:
    DISPLAY("Green")
else:
    DISPLAY("Not Green")

Spinner Design

  • The spinner design includes:

    • A blue section which occupies ½ (1/2) of the spinner.

    • Equal-sized orange and purple sections.

Pseudocode for Spinner Outcomes

IF RANDOM(1,4) = 1:
    DISPLAY "blue"
ELSE:
    IF RANDOM(1,2) = 1:
        DISPLAY "orange"
    ELSE:
        DISPLAY "purple"

Vocabulary

  • Sequencing

  • Selection

  • Iteration

  • Abstraction

  • Control Structure

  • Sequential Programming

  • Arithmetic Operator

  • Logical Operators

  • Comparison Operator

  • Truth Table

To Do In Class

  • Control Structures Lab

  • Catch up on Code HS

  • Complete Code HS 4.12 Practice Quiz