Implement 2019 day 3

2019/aoc2019/day03.py

@@ -0,0 +1,44 @@
+import itertools
+from typing import Dict, TextIO
+
+
+def compute_points(line: str) -> Dict[complex, int]:
+    points: Dict[complex, int] = {}
+    steps = itertools.count(1)
+
+    pos = complex(0)
+
+    directions = {
+        'U': 1j,
+        'R': 1,
+        'D': -1j,
+        'L': -1,
+    }
+
+    for move in line.strip().split(','):
+        direction = directions[move[0]]
+
+        for _ in range(int(move[1:])):
+            pos += direction
+
+            points.setdefault(pos, next(steps))
+
+    return points
+
+
+def part1(data: TextIO) -> int:
+    points_a = compute_points(next(data))
+    points_b = compute_points(next(data))
+
+    in_common = set(points_a.keys()) & set(points_b.keys())
+
+    return int(min(abs(c.imag) + abs(c.real) for c in in_common))
+
+
+def part2(data: TextIO) -> int:
+    points_a = compute_points(next(data))
+    points_b = compute_points(next(data))
+
+    in_common = set(points_a.keys()) & set(points_b.keys())
+
+    return min(points_a[pos] + points_b[pos] for pos in in_common)