Day 7

day7.py

MAX_DIR_SIZE = 100_000
REQUIRED_SPACE = 0


def calculate_deletable(file_system):
    total = 0
    for v in file_system.values():
        if isinstance(v, int):
            total += v if v <= MAX_DIR_SIZE else 0
        if isinstance(v, dict):
            total += calculate_deletable(v)
    return total


def find_deletable(file_system):
    deletable = []
    for v in file_system.values():
        if isinstance(v, int):
            if v >= REQUIRED_SPACE:
                deletable.append(v)
        if isinstance(v, dict):
            item = find_deletable(v)
            if item:
                deletable += item
    return deletable
    
    
def get_dir(file_system, parents):
    directory = file_system
    for parent in parents:
        directory = directory[parent]
    return directory


def build_filesystem(commands, file_system=None, parents=None):
    file_system = file_system or {'size': 0}
    if not len(commands):
        return file_system
    
    command = commands.pop(0)
    if command[0].startswith('cd'):
        input = command[0].split()[1]
        if input == '/':
            return build_filesystem(commands, file_system, parents=[])
        elif input == '..':
            parents.pop()
            return build_filesystem(commands, file_system, parents=parents)
        else:
            parents.append(input)
            return build_filesystem(commands, file_system, parents=parents)
            
    elif command[0].startswith('ls'):
        output = command[1:]
        
        current_dir = get_dir(file_system, parents)
        parent_dir = get_dir(file_system, parents[:-1])
        
        for item in output:
            if item.startswith('dir'):
                key = item.split()[1]
                current_dir.update({key: {'size': 0}})
            else:
                value, key = item.split()
                if 'size' in current_dir:
                    current_dir['size'] += int(value)
                else:
                    current_dir['size'] = int(value)
                
                for count, _ in enumerate(parents):
                    parent_dir = get_dir(file_system, parents[:-count])
                    if parent_dir != current_dir:
                        parent_dir['size'] += int(value)
                
        return build_filesystem(commands, file_system, parents=parents)

    
def get_command_line(input):
    return [[x.strip() for x in i.splitlines()] for i in input.split('$') if i and i != '\n']

with open('data/day7.txt') as _file:
    commands = get_command_line(_file.read())
    file_system = build_filesystem(commands)
    
    # Part 1
    total = calculate_deletable(file_system)
    print('Part 1:', total)
    assert total == 1844187

    # Part 2 - ERROR
    deletable_dirs = find_deletable(file_system)
    print('Part 2:', min(deletable_dirs))