Poetry stuff.

src/holt59/aoc/2023/day18.py

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+import sys
+from typing import Literal, TypeAlias, cast
+
+Direction: TypeAlias = Literal["R", "L", "U", "D"]
+
+DIRECTIONS: list[Direction] = ["R", "D", "L", "U"]
+MOVES: dict[Direction, tuple[int, int]] = {
+    "R": (0, +1),
+    "L": (0, -1),
+    "U": (-1, 0),
+    "D": (+1, 0),
+}
+
+
+def area(corners: list[tuple[int, int]], perimeter: int) -> int:
+    area = abs(
+        sum(c0[0] * c1[1] - c0[1] * c1[0] for c0, c1 in zip(corners, corners[1::])) // 2
+    )
+    return 1 + area - perimeter // 2 + perimeter
+
+
+def polygon(values: list[tuple[Direction, int]]) -> tuple[list[tuple[int, int]], int]:
+    perimeter = 0
+    corners: list[tuple[int, int]] = [(0, 0)]
+    for direction, amount in values:
+        perimeter += amount
+        corners.append(
+            (
+                corners[-1][0] + amount * MOVES[direction][0],
+                corners[-1][1] + amount * MOVES[direction][1],
+            )
+        )
+    return corners, perimeter
+
+
+lines = sys.stdin.read().splitlines()
+
+
+# part 1
+answer_1 = area(
+    *polygon([(cast(Direction, (p := line.split())[0]), int(p[1])) for line in lines])
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = area(
+    *polygon(
+        [
+            (DIRECTIONS[int((h := line.split()[-1])[-2])], int(h[2:-2], 16))
+            for line in lines
+        ]
+    )
+)
+print(f"answer 2 is {answer_2}")