2015 day 3.

src/holt59/aoc/2015/day3.py

@@ -0,0 +1,34 @@
+import sys
+from collections import defaultdict
+
+line = sys.stdin.read().strip()
+
+
+def process(directions: str) -> dict[tuple[int, int], int]:
+    counts: dict[tuple[int, int], int] = defaultdict(lambda: 0)
+    counts[0, 0] = 1
+    x, y = (0, 0)
+
+    for c in directions:
+        match c:
+            case ">":
+                x += 1
+            case "<":
+                x -= 1
+            case "^":
+                y -= 1
+            case "v":
+                y += 1
+            case _:
+                raise ValueError()
+
+        counts[x, y] += 1
+
+    return counts
+
+
+answer_1 = len(process(line))
+print(f"answer 1 is {answer_1}")
+
+answer_2 = len(process(line[::2]) | process(line[1::2]))
+print(f"answer 2 is {answer_2}")