day25 finished

advent/days/day25/solution.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+from typing import Iterator
+
+day_num = 25
+
+
+def part1(lines: Iterator[str]) -> str:
+    snafu = sum(from_snafu(line) for line in lines)
+    return to_snafu(snafu)
+
+
+def part2(lines: Iterator[str]) -> None:
+    return None
+
+
+SNAFU = "=-012"
+
+
+def from_snafu(line: str) -> int:
+    result = 0
+    for char in line:
+        result = result * 5 + SNAFU.index(char) - 2
+    return result
+
+
+def to_snafu(number: int) -> str:
+    result = ""
+    while number > 0:
+        mod = (number + 2) % 5
+        result = SNAFU[mod] + result
+        number = (number - mod + 2) // 5
+    return result