Poetry stuff.

src/holt59/aoc/2021/day3.py

@@ -0,0 +1,39 @@
+import sys
+from collections import Counter
+from typing import Literal
+
+
+def generator_rating(
+    values: list[str], most_common: bool, default: Literal["0", "1"]
+) -> str:
+    index = 0
+    most_common_idx = 0 if most_common else 1
+
+    while len(values) > 1:
+        cnt = Counter(value[index] for value in values)
+        bit = cnt.most_common(2)[most_common_idx][0]
+        if cnt["0"] == cnt["1"]:
+            bit = default
+        values = [value for value in values if value[index] == bit]
+        index += 1
+
+    return values[0]
+
+
+lines = sys.stdin.read().splitlines()
+
+
+# part 1
+most_and_least_common = [
+    tuple(Counter(line[col] for line in lines).most_common(2)[m][0] for m in range(2))
+    for col in range(len(lines[0]))
+]
+gamma_rate = int("".join(most for most, _ in most_and_least_common), base=2)
+epsilon_rate = int("".join(least for _, least in most_and_least_common), base=2)
+print(f"answer 1 is {gamma_rate * epsilon_rate}")
+
+# part 2
+oxygen_generator_rating = int(generator_rating(lines, True, "1"), base=2)
+co2_scrubber_rating = int(generator_rating(lines, False, "0"), base=2)
+answer_2 = oxygen_generator_rating * co2_scrubber_rating
+print(f"answer 2 is {answer_2}")