#!/usr/bin/env python3
import re

INPUT_FILE = 'input'

cd_pattern = '^\$\scd (.*)$'
ls_pattern = '^\$ ls$'
dir_pattern = '^dir .*$'
file_pattern = '^(\d+) .*$'

total_space = 70000000
required_free = 30000000

def main():
    content = map(str.strip, open(INPUT_FILE, 'r').readlines())
    cwd = ['']
    folders = {}
    for line in content:
        if re.match(dir_pattern, line) or re.match(ls_pattern, line):
            # ignore `dir a` and `$ ls`
            continue
        cd = re.match(cd_pattern, line)
        if cd:
            new_dir = cd.group(1)
            if new_dir == '..':
                cwd.pop()
            else:
                cwd.append(new_dir)
                folders['/'.join(cwd)] = 0
            print('/'.join(cwd))
            continue
        file_match = re.match(file_pattern, line)
        if file_match:
            filesize = int(file_match.group(1))
            for n in range(len(cwd), 0, -1):
                try:
                    folders['/'.join(cwd[:n])] += filesize
                except KeyError:
                    continue
        else:
            print('ERROR: No regex matched for {}'.format(line()))
    print(folders)
    used_space = folders['//']
    free_space = total_space - used_space
    print('total: {} used: {} free: {}'.format(total_space, used_space, free_space))
    space_needed = required_free - free_space
    print('Need {}'.format(space_needed))
    candidates = []
    for key in folders.keys():
        if folders[key] >= space_needed:
            candidates.append(folders[key])
    print('Result: {}'.format(min(candidates)))

if __name__ == '__main__':
    main()