Problem 3

(*) Find the K'th element of a list. Solutions

The first element in the list is number 1. Example:

* (element-at '(a b c d e) 3)
c

Example in Haskell:

elementAt [1,2,3] 2

2

elementAt "haskell" 5

'e'

Problem 2

(*) Find the last-but-one (or second-last) element of a list.

(Note that the Lisp transcription of this problem is incorrect.)

Example in Haskell:

myButLast [1,2,3,4]

3

myButLast ['a'..'z']

'y'

Source: https://wiki.haskell.org/index.php?title=99_questions%2F1_to_10

Problem 2

(*) Find the last-but-one (or second-last) element of a list. Solutions

(Note that the Lisp transcription of this problem is incorrect.)

Example in Haskell:

myButLast [1,2,3,4]

3

myButLast ['a'..'z']

'y'

Problem 1

(*) Find the last element of a list. Solutions

(Note that the Lisp transcription of this problem is incorrect.)

Example in Haskell:

myLast [1,2,3,4]

4

myLast ['x','y','z']

'z'

cross-posted from: https://feddit.org/post/14593429

Factorial Calculator

Difficulty: Expert

Game Overview

Design a physical track where a marble rolls and executes programming instructions. The marble carries a value and performs calculations as it hits different track pieces.

Puzzle

Calculate the factorial of 4 (4! = 4 × 3 × 2 × 1) and output the result 24.

Starting Conditions:

• Marble begins carrying the value: 4
• Expected output: 24

Available Track Pieces (Use Each Once):

• 2× CURVE - Changes marble direction 90°
• 1× STRAIGHT - Continues marble in same direction
• 1× LOOP-TRACK - Connects track to form a physical loop
• 1× BRANCH-ZERO - Marble goes LEFT if carrying 0, RIGHT otherwise
• 1× SUBTRACT-1 - Subtracts 1 from marble's value
• 1× MULTIPLY - Multiplies marble's value by memory slot A
• 1× STORE-A - Saves marble's current value to memory slot A
• 1× LOAD-A - Loads value from memory slot A into marble
• 1× OUTPUT - Displays marble's current value
• 1× HALT - Stops the marble

Rules:

• Arrange all track pieces to create a complete path
• Marble executes instructions when rolling over pieces
• Design must calculate factorial using the loop mechanism
• Marble must output 24 and then halt

Goal

The marble completes its journey, outputs 24, and stops.

Factorial Calculator

Difficulty: Expert

Game Overview

Design a physical track where a marble rolls and executes programming instructions. The marble carries a value and performs calculations as it hits different track pieces.

Puzzle

Calculate the factorial of 4 (4! = 4 × 3 × 2 × 1) and output the result 24.

Starting Conditions:

• Marble begins carrying the value: 4
• Expected output: 24

Available Track Pieces (Use Each Once):

• 2× CURVE - Changes marble direction 90°
• 1× STRAIGHT - Continues marble in same direction
• 1× LOOP-TRACK - Connects track to form a physical loop
• 1× BRANCH-ZERO - Marble goes LEFT if carrying 0, RIGHT otherwise
• 1× SUBTRACT-1 - Subtracts 1 from marble's value
• 1× MULTIPLY - Multiplies marble's value by memory slot A
• 1× STORE-A - Saves marble's current value to memory slot A
• 1× LOAD-A - Loads value from memory slot A into marble
• 1× OUTPUT - Displays marble's current value
• 1× HALT - Stops the marble

Rules:

• Arrange all track pieces to create a complete path
• Marble executes instructions when rolling over pieces
• Design must calculate factorial using the loop mechanism
• Marble must output 24 and then halt

Goal

The marble completes its journey, outputs 24, and stops.

cross-posted from: https://feddit.org/post/14591777

Game Description:

PaperBugs is a puzzle where you control bugs on a grid by writing a simple program. Each bug executes the same program step-by-step to reach their targets. The key challenge is that ALL bugs run the SAME program simultaneously!

Puzzle:

Available instructions:

• MOVE - move forward one cell
• LEFT / RIGHT - rotate 90 degrees
• IF FLOWER - execute next line only if flower ahead
• IF EMPTY - execute next line only if path clear
• IF WALL - execute next line only if wall ahead
• IF GEM - execute next line only if gem ahead

Board:

Legend:

• Flower (blocks movement)
• Gem (collectable)
• Wall (blocks movement)

Goal:

Write a single program that guides both bugs to collect gems and reach their targets safely.