140 lines
4.6 KiB
Python
140 lines
4.6 KiB
Python
"""
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--- Day 7: No Space Left On Device ---
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You can hear birds chirping and raindrops hitting leaves as the
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expedition proceeds. Occasionally, you can even hear much louder sounds
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in the distance; how big do the animals get out here, anyway?
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The device the Elves gave you has problems with more than just its
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communication system. You try to run a system update:
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$ system-update --please --pretty-please-with-sugar-on-top
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Error: No space left on device
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Perhaps you can delete some files to make space for the update?
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You browse around the filesystem to assess the situation and save the
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resulting terminal output (your puzzle input). For example:
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$ cd /
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$ ls
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dir a
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14848514 b.txt
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8504156 c.dat
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dir d
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$ cd a
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$ ls
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dir e
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29116 f
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2557 g
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62596 h.lst
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$ cd e
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$ ls
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584 i
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$ cd ..
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$ cd ..
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$ cd d
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$ ls
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4060174 j
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8033020 d.log
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5626152 d.ext
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7214296 k
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The filesystem consists of a tree of files (plain data) and directories
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(which can contain other directories or files). The outermost directory
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is called /. You can navigate around the filesystem, moving into or out
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of directories and listing the contents of the directory you're
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currently in.
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Within the terminal output, lines that begin with $ are commands you
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executed, very much like some modern computers:
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- cd means change directory. This changes which directory is the current
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directory, but the specific result depends on the argument:
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- cd x moves in one level: it looks in the current directory for the
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directory named x and makes it the current directory.
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- cd .. moves out one level: it finds the directory that contains the
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current directory, then makes that directory the current directory.
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- cd / switches the current directory to the outermost directory, /.
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- ls means list. It prints out all of the files and directories
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immediately contained by the current directory:
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- 123 abc means that the current directory contains a file named abc
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with size 123.
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- dir xyz means that the current directory contains a directory named
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xyz.
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Given the commands and output in the example above, you can determine
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that the filesystem looks visually like this:
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- / (dir)
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- a (dir)
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- e (dir)
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- i (file, size=584)
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- f (file, size=29116)
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- g (file, size=2557)
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- h.lst (file, size=62596)
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- b.txt (file, size=14848514)
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- c.dat (file, size=8504156)
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- d (dir)
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- j (file, size=4060174)
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- d.log (file, size=8033020)
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- d.ext (file, size=5626152)
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- k (file, size=7214296)
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Here, there are four directories: / (the outermost directory), a and d
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(which are in /), and e (which is in a). These directories also contain
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files of various sizes.
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Since the disk is full, your first step should probably be to find
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directories that are good candidates for deletion. To do this, you need
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to determine the total size of each directory. The total size of a
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directory is the sum of the sizes of the files it contains, directly or
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indirectly. (Directories themselves do not count as having any intrinsic
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size.)
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The total sizes of the directories above can be found as follows:
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- The total size of directory e is 584 because it contains a single file
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i of size 584 and no other directories.
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- The directory a has total size 94853 because it contains files f (size
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29116), g (size 2557), and h.lst (size 62596), plus file i indirectly
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(a contains e which contains i).
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- Directory d has total size 24933642.
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- As the outermost directory, / contains every file. Its total size is
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48381165, the sum of the size of every file.
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To begin, find all of the directories with a total size of at most
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100000, then calculate the sum of their total sizes. In the example
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above, these directories are a and e; the sum of their total sizes is
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95437 (94853 + 584). (As in this example, this process can count files
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more than once!)
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Find all of the directories with a total size of at most 100000. What
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is the sum of the total sizes of those directories?
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"""
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from utils import Dir, parse_commands_to_tree, print_tree
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def main():
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with open("input.txt", "r", encoding="utf-8") as input_file:
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tree = parse_commands_to_tree(input_file.read().split("\n"))
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print_tree(tree)
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def find_large_dirs(directory):
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total_size = 0
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for thing in directory.contents:
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if isinstance(thing, Dir):
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if thing.size < 100000:
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total_size += thing.size
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total_size += find_large_dirs(thing)
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return total_size
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total_size = find_large_dirs(tree)
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print(f"Total size: {total_size}")
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if __name__ == "__main__":
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main()
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