day 7

flake.nix

@@ -7,7 +7,7 @@
 
         devShell = pkgs.mkShell {
           packages = with pkgs; [
-            python3
+            (python3.withPackages (p: with p; [ more-itertools ]))
             ruby
             swiProlog
             yabasic

py-ver/07.py

@@ -0,0 +1,106 @@
+from pathlib import *
+from queue import Queue
+from more_itertools import peekable
+
+with open("07.txt") as f:
+  data = f.read()
+ex_data = """$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k"""
+
+def build_fs(data):
+  fs = dict()
+  cur_dir = PosixPath("/")
+  it = peekable(data.splitlines())
+
+  def addfssize(dir, num):
+    size, children = fs[dir]
+    fs[dir] = (size + num, children)
+
+  while True:
+    try: line = next(it)
+    except StopIteration: break
+    line = line.strip()
+
+    if line.startswith("$"):
+      line = line.strip("$ ")
+      parts = line.split(" ")
+      cmd = parts[0]
+
+      if cmd == "cd":
+        path = PosixPath(parts[1])
+        if path.is_absolute(): cur_dir = path
+        else: cur_dir = cur_dir.joinpath(parts[1]).resolve()
+
+        if cur_dir not in fs: fs[cur_dir] = (0, dict())
+      elif cmd == "ls":
+        while True:
+          try: outline = it.peek()
+          except StopIteration: break
+          if outline.startswith("$"): break
+          outline = next(it)
+
+          size, name = outline.split(" ")
+          if size == "dir":
+            fs[cur_dir][1][name] = None
+          else:
+            size = int(size)
+            fs[cur_dir][1][name] = size
+
+            dir = cur_dir
+            while dir.parent != dir:
+              addfssize(dir, size)
+              dir = dir.parent
+            addfssize(dir, size)
+
+  return fs
+
+def solve1(data):
+  fs = build_fs(data)
+
+  sum = 0
+  for dir, (size, children) in fs.items():
+    if size <= 100000:
+      sum += size
+  print(sum)
+
+def solve2(data):
+  fs = build_fs(data)
+
+  needed_space = 30000000
+  free_space = 70000000 - fs[PosixPath("/")][0]
+  remaining_space = needed_space - free_space
+
+  ans = needed_space + 1
+
+  for dir, (size, children) in fs.items():
+    if size >= remaining_space:
+      ans = min(ans, size)
+
+  print(ans)
+
+solve1(ex_data)
+solve1(data)
+
+solve2(ex_data)
+solve2(data)