day3-multiple-compartments.py

import sys

total = 0

# Read the input file from the command line arguments
with open(sys.argv[1], "r") as f:
    # Initialize a list to store the lines in groups of three
    group = []

    # Read each line of the input file
    for line in f:
        # Add the line to the current group
        group.append(line)

        # If the group has three lines, process it
        if len(group) == 3:
            # Split each rucksack into its three compartments
            compartments = [line[i:i+len(line)//3] for i in range(0, len(line), len(line)//3)]

            # Iterate through each character in the first compartment of the first rucksack
            for ch in compartments[0]:
                # If the character also appears in the other compartments,
                # add its priority to the running total
                if all(ch in comp for comp in compartments[1:]):
                    # Lowercase item types have priorities 1 through 26
                    if ch.islower():
                        total += ord(ch) - ord("a") + 1
                    # Uppercase item types have priorities 27 through 52
                    elif ch.isupper():
                        total += ord(ch) - ord("A") + 27

            # Clear the group
            group = []

# Print the sum of the priorities of the item types that correspond to the badges
# of each group
print(total)