152 lines
6.3 KiB
Plaintext
152 lines
6.3 KiB
Plaintext
Advent of Code
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br0xen (AoC++) 14*
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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 expedition proceeds. Occasionally, you can even hear
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much louder sounds 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 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 resulting terminal output (your puzzle input). For
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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 (which can contain other directories or files).
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The outermost directory is called /. You can navigate around the filesystem, moving into or out of directories and
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listing the contents of the directory you're currently in.
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Within the terminal output, lines that begin with $ are commands you executed, very much like some modern computers:
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• cd means change directory. This changes which directory is the current directory, but the specific result depends on
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the argument:
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• cd x moves in one level: it looks in the current directory for the directory named x and makes it the current
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directory.
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• cd .. moves out one level: it finds the directory that contains the current directory, then makes that
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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 immediately contained by the current directory:
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• 123 abc means that the current directory contains a file named abc with size 123.
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• dir xyz means that the current directory contains a directory named xyz.
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Given the commands and output in the example above, you can determine 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 (which are in /), and e (which is in a). These
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directories also contain files of various sizes.
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Since the disk is full, your first step should probably be to find directories that are good candidates for deletion. To
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do this, you need to determine the total size of each directory. The total size of a directory is the sum of the sizes
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of the files it contains, directly or indirectly. (Directories themselves do not count as having any intrinsic 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 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 29116), g (size 2557), and h.lst (size
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62596), plus file i indirectly (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 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 100000, then calculate the sum of their total sizes.
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In the example above, these directories are a and e; the sum of their total sizes is 95437 (94853 + 584). (As in this
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example, this process can count files more than once!)
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Find all of the directories with a total size of at most 100000. What is the sum of the total sizes of those
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directories?
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Your puzzle answer was 1642503.
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--- Part Two ---
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Now, you're ready to choose a directory to delete.
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The total disk space available to the filesystem is 70000000. To run the update, you need unused space of at least
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30000000. You need to find a directory you can delete that will free up enough space to run the update.
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In the example above, the total size of the outermost directory (and thus the total amount of used space) is 48381165;
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this means that the size of the unused space must currently be 21618835, which isn't quite the 30000000 required by the
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update. Therefore, the update still requires a directory with total size of at least 8381165 to be deleted before it can
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run.
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To achieve this, you have the following options:
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• Delete directory e, which would increase unused space by 584.
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• Delete directory a, which would increase unused space by 94853.
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• Delete directory d, which would increase unused space by 24933642.
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• Delete directory /, which would increase unused space by 48381165.
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Directories e and a are both too small; deleting them would not free up enough space. However, directories d and / are
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both big enough! Between these, choose the smallest: d, increasing unused space by 24933642.
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Find the smallest directory that, if deleted, would free up enough space on the filesystem to run the update. What is
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the total size of that directory?
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Your puzzle answer was 6999588.
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Both parts of this puzzle are complete! They provide two gold stars: **
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References
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Visible links
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. https://adventofcode.com/
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. https://adventofcode.com/2022/about
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. Advent of Code Supporter
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https://adventofcode.com/2022/support
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/sponsors
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. https://adventofcode.com/2022/stats
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. https://adventofcode.com/2022/sponsors
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/day/7/input
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