add_problem.sh

    #!/bin/bash

    # Check for correct argument count
    if [ "$#" -ne 4 ]; then
    echo "Usage: $0 <difficulty: easy|medium|hard> <number> <name_with_underscores> <extension>"
    exit 1
    fi

    # Parse arguments
    difficulty=$1
    number=$(printf "%04d" "$2")
    name_snake=$3
    ext=$4

    # Validate difficulty
    case "$difficulty" in
    easy|medium|hard) ;;
    *)
        echo "Invalid difficulty. Use: easy, medium, or hard."
        exit 1
        ;;
    esac

    # Validate name: only lowercase letters, underscores, and numbers
    if [[ ! "$name_snake" =~ ^[a-z0-9_]+$ ]]; then
    echo "Invalid name. Use only lowercase letters, numbers, and underscores."
    exit 1
    fi

    # Compose the problem folder name
    target_dir="${difficulty}/${number}_${name_snake}"

    # Create the problem directory and solution file
    mkdir -p "$target_dir"
    touch "${target_dir}/solution.${ext}"

    echo "Added ${target_dir}/solution.${ext}"