Implement 2019 day 8

2019/aoc2019/day08.py

@@ -0,0 +1,33 @@
+from collections import Counter
+from typing import Iterable, TextIO
+
+import numpy  # type: ignore
+
+
+def parse_layers(width: int, height: int, data: TextIO) -> Iterable[numpy.array]:
+    chunk_size = width * height
+
+    content = next(data).strip()
+
+    for pos in range(0, len(content), chunk_size):
+        yield numpy.array([int(c) for c in content[pos:pos + chunk_size]])
+
+
+def part1(data: TextIO) -> int:
+    best_layer: Counter[int] = min((Counter(layer) for layer in parse_layers(25, 6, data)), key=lambda c: c[0])
+
+    return best_layer[1] * best_layer[2]
+
+
+def format_row(row: Iterable[int]) -> str:
+    return ''.join('#' if p == 1 else ' ' for p in row)
+
+
+def part2(data: TextIO) -> str:
+    layers = list(parse_layers(25, 6, data))
+    background = numpy.zeros(25 * 6, numpy.int8)
+
+    for layer in reversed(layers):
+        background[layer != 2] = layer[layer != 2]
+
+    return '\n'.join(format_row(row) for row in background.reshape(6, 25))