2022 Day 07

#!/usr/bin/env python3

import sys

PART1_SIZE      = 100000
TOTAL_DISKSPACE = 70000000
PART2_TARGET    = 30000000

class Dir(object):
    def __init__(self,name,parent):
        self.name = name
        self.parent = parent
        self.contents = []

    def size(self):
        return sum([item.size() for item in self.contents])

    def full_path(self):
        if self.parent is None: return self.name
        return self.name+"/"+self.parent.full_path()

class File(object):
    def __init__(self,name,parent,size):
        self.name = name
        self.parent = parent
        self._size = size

    def size(self):
        return self._size

    def __repr__(self):
        return f"{self.name} ({self.size})"

def dirsum(d):
    size = 0
    for subdir in d.contents:
        if type(subdir) == Dir: size += dirsum(subdir)
    if d.size() <= PART1_SIZE: size += d.size()
    return size

def smallest_dir_larger_than(d,minsize,bestsize):
    new_best = bestsize
    newsize = d.size()
    if newsize >= minsize and newsize < bestsize:
        new_best = newsize
    for subdir in d.contents:
        if type(subdir) == Dir:
            new_best = smallest_dir_larger_than(subdir,minsize,new_best)
    return new_best

def main():
    # Input
    args = sys.argv
    input_file = args[1]
    input_file = file_lines(input_file)

    # Generate filesystem
    filesystem = Dir("/",None)
    pwd = filesystem
    for cmd in input_file:
        if cmd[0] == "$":
            # Issue command
            cmd = cmd[2:]
            if cmd == "cd /":
                pwd = filesystem
            elif cmd == "cd ..":
                pwd = pwd.parent
            elif cmd == "ls":
                pass
            else:
                if cmd.split(" ")[0] == "cd":
                    target = cmd.split(" ")[1]
                    pwd = next((x for x in pwd.contents if x.name == target and type(x) == Dir), None)
                else:
                    quit(f"{cmd}: command not found...")

        else:
            # ls output
            parts = cmd.split(" ")
            if parts[0] == "dir":
                # dir
                dirname = parts[1]
                pwd.contents.append(Dir(dirname,pwd))
            else:
                # file
                filename,sz = parts[1],int(parts[0])
                pwd.contents.append(File(filename,pwd,sz))

    # Part 1
    print("Part 1: ",dirsum(filesystem)) # 1770595

    # Part 2
    total_used = filesystem.size()
    available = TOTAL_DISKSPACE - total_used
    minimum_free = PART2_TARGET - available
    print("Part 2: ",smallest_dir_larger_than(filesystem,minimum_free,TOTAL_DISKSPACE)) # 2195372

def file_lines(file):
    with open(file) as f:
        data = [line.rstrip() for line in f]
    return data

if __name__ == "__main__":
    main()