Poetry stuff.

src/holt59/aoc/2022/day7.py

@@ -0,0 +1,80 @@
+import sys
+from pathlib import Path
+
+lines = sys.stdin.read().splitlines()
+
+# we are going to use Path to create path and go up/down in the file tree since it
+# implements everything we need
+#
+# we can use .resolve() to get normalized path, although this will add C:\ to all paths
+# on Windows but that is not an issue since only the sizes matter
+#
+
+# mapping from path to list of files or directories
+trees: dict[Path, list[Path]] = {}
+
+# mapping from paths to either size (for file) or -1 for directory
+sizes: dict[Path, int] = {}
+
+# first line must be a cd otherwise we have no idea where we are
+assert lines[0].startswith("$ cd")
+base_path = Path(lines[0].strip("$").split()[1]).resolve()
+cur_path = base_path
+
+trees[cur_path] = []
+sizes[cur_path] = -1
+
+for line in lines[1:]:
+    # command
+    if line.startswith("$"):
+        parts = line.strip("$").strip().split()
+        command = parts[0]
+
+        if command == "cd":
+            cur_path = cur_path.joinpath(parts[1]).resolve()
+
+            # just initialize the lis of files if not already done
+            if cur_path not in trees:
+                trees[cur_path] = []
+        else:
+            # nothing to do here
+            pass
+
+    # fill the current path
+    else:
+        parts = line.split()
+        name: str = parts[1]
+        if line.startswith("dir"):
+            size = -1
+        else:
+            size = int(parts[0])
+
+        path = cur_path.joinpath(name)
+        trees[cur_path].append(path)
+        sizes[path] = size
+
+
+def compute_size(path: Path) -> int:
+    size = sizes[path]
+
+    if size >= 0:
+        return size
+
+    return sum(compute_size(sub) for sub in trees[path])
+
+
+acc_sizes = {path: compute_size(path) for path in trees}
+
+# part 1
+answer_1 = sum(size for size in acc_sizes.values() if size <= 100_000)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+total_space = 70_000_000
+update_space = 30_000_000
+free_space = total_space - acc_sizes[base_path]
+
+to_free_space = update_space - free_space
+
+answer_2 = min(size for size in acc_sizes.values() if size >= to_free_space)
+print(f"answer 2 is {answer_2}")