2017: d22: ex1: add solution

2017/d22/ex1/ex1.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+
+import dataclasses
+import enum
+import sys
+from typing import NamedTuple
+
+
+class Point(NamedTuple):
+    x: int
+    y: int
+
+
+class Direction(enum.Enum):
+    UP = Point(-1, 0)
+    DOWN = Point(1, 0)
+    LEFT = Point(0, -1)
+    RIGHT = Point(0, 1)
+
+    def left(self) -> "Direction":
+        x, y = self.value
+        return Direction(Point(-y, x))
+
+    def right(self) -> "Direction":
+        x, y = self.value
+        return Direction(Point(y, -x))
+
+    def apply(self, p: Point) -> Point:
+        dx, dy = self.value
+        return Point(p.x + dx, p.y + dy)
+
+
+@dataclasses.dataclass
+class Carrier:
+    pos: Point
+    dir: Direction
+
+    def burst(self, infected: set[Point]) -> bool:
+        infect = False
+        if self.pos in infected:
+            self.dir = self.dir.right()
+            infected.remove(self.pos)
+        else:
+            self.dir = self.dir.left()
+            infected.add(self.pos)
+            infect = True
+        self.pos = self.dir.apply(self.pos)
+        return infect
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> set[Point]:
+        return {
+            Point(x, y)
+            for x, line in enumerate(input.splitlines())
+            for y, c in enumerate(line)
+            if c == "#"
+        }
+
+    infected = parse(input)
+    middle = len(input.splitlines()) // 2
+    carrier = Carrier(Point(middle, middle), Direction.UP)
+    total = 0
+
+    for _ in range(10000):
+        total += carrier.burst(infected)
+    return total
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()