2015: d03: ex1: add solution

2015/d03/ex1/ex1.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+import enum
+import sys
+from typing import NamedTuple
+
+
+class Point(NamedTuple):
+    x: int
+    y: int
+
+
+class Direction(enum.StrEnum):
+    NORTH = "^"
+    EAST = ">"
+    SOUTH = "v"
+    WEST = "<"
+
+    def apply(self, p: Point) -> Point:
+        match self:
+            case Direction.NORTH:
+                dx, dy = -1, 0
+            case Direction.EAST:
+                dx, dy = 0, 1
+            case Direction.SOUTH:
+                dx, dy = 1, 0
+            case Direction.WEST:
+                dx, dy = 0, -1
+        return Point(p.x + dx, p.y + dy)
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> list[Direction]:
+        return [Direction(c) for c in input.strip()]
+
+    def distribute_presents(moves: list[Direction]) -> set[Point]:
+        pos = Point(0, 0)
+        seen = {pos}
+        for move in moves:
+            pos = move.apply(pos)
+            seen.add(pos)
+        return seen
+
+    moves = parse(input)
+    presents = distribute_presents(moves)
+    return len(presents)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()