day 18

1 files changed, 43 insertions, 0 deletions

diff --git a/18.py b/18.py
new file mode 100644
index 0000000..a294ee2
--- /dev/null
+++ b/18.py
@@ -0,0 +1,43 @@
+from collections.abc import Iterable
+from dataclasses import dataclass
+from itertools import islice
+from sys import stdin
+from typing import Self, Type
+
+
+@dataclass
+class Instruction:
+    direction: str
+    distance: int
+
+    @classmethod
+    def from_str(cls: Type[Self], s: str) -> tuple[Self, Self]:
+        direction, distance, colour = s.split(" ")
+        colour = colour.strip("()#")
+        colour_dist = int(colour[:-1], 16)
+        colour_dir = "RDLU"[int(colour[-1], 16)]
+        return cls(direction, int(distance)), cls(colour_dir, colour_dist)
+
+
+inp = [Instruction.from_str(l.rstrip("\n")) for l in stdin]
+
+
+def solve(instructions: Iterable[Instruction]) -> int:
+    dirmap = {"U": (0, -1), "D": (0, 1), "L": (-1, 0), "R": (1, 0)}
+    pos = (0, 0)
+    area = 0
+    border = 0
+    for ins in instructions:
+        direction = dirmap[ins.direction]
+        newpos = (
+            pos[0] + direction[0] * (ins.distance),
+            pos[1] + direction[1] * (ins.distance),
+        )
+        area += pos[0] * newpos[1] - newpos[0] * pos[1]
+        border += ins.distance
+        pos = newpos
+    return (border + area) // 2 + 1
+
+
+print(solve(ins for ins, _ in inp))
+print(solve(ins for _, ins in inp))