Problem 3

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

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

 undefined

    
* (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

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× HAL

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.

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.

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.

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. Heavy bugs have special abilities! 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 ROCK - execute next line only if rock ahead
• PUSH - push a rock forward (Heavy Bug only)

Puzzle:

Special Rule: Heavy Bug can push rocks with the PUSH command, but only into empty spaces.

Goal:

Push rocks to create a safe path and reach the target.

Puzzle Description:

PaperBugs is a little 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.

Instructions:

• MOVE - move forward one cell
• LEFT / RIGHT - rotate 90 degrees
• IF FLOWER - execute next line only if flower ahead (the next cell the bug is currently facing)
• IF EMPTY - execute next line only if path clear

Puzzle - "Avoid the flower" (Easy)

• [ ][ ][T]
• [B][F][ ]
• [ ][ ][ ]

Legend:

• B: Bug (starts facing right)
• T: Target
• F: Flower
• [ ]: Empty space

Goal: Get the bug to the target.

Abstract

Federated learning provides an effective solution to the data privacy issue in distributed machine learning. However, distributed federated learning systems are inherently susceptible to data poisoning attacks and data heterogeneity. Under conditions of high data heterogeneity, the gradient conflict problem in federated learning becomes more pronounced, making traditional defense mechanisms against poisoning attacks less adaptable between scenarios with and without attacks. To address this challenge, we design a two-stage federated learning framework for defending against poisoning attacks—FedCVG. During implementation, FedCVG first removes malicious clients using a reputation-based clustering method, and then optimizes communication overhead through a virtual aggregation mechanism. Extensive experimental results show that, compared to other baseline methods, FedCVG improves average accuracy by 4.2% and reduces communication overhead by approximately 50% while defending a

Abstract: Distributed machine learning (DML) may become an important component of IoT device fleets and smart homes in the future. However, it currently presents challenges where reliable (or frequent) internet connectivity is necessary, or trust is not handled. Since DML is generally decentralized and often relies on peer-to-peer networks, we argue that BitTorrent as a time-proven protocol in this space could aid in building a solution. This paper explores the possibilities of employing BitTorrent mechanisms for gossip-based DML. It provides initial evidence supporting the viability of this approach by analysing the behaviour of model training in a simulator representing 30 individual peers with distinct data sets.