2015 day 25.

src/holt59/aoc/2015/day25.py

@@ -0,0 +1,16 @@
+import re
+from typing import Any, Iterator
+
+from ..base import BaseSolver
+from ..tools.math import pow_mod
+
+
+class Solver(BaseSolver):
+    def solve(self, input: str) -> Iterator[Any]:
+        m = re.search(r"row\s*([0-9]+)\s*,\s*column\s*([0-9]+)", input)
+        assert m is not None
+
+        row, col = int(m.group(1)), int(m.group(2))
+        n = (row * (row - 1)) // 2 + col * (col + 1) // 2 + (row - 1) * (col - 1)
+
+        yield (20151125 * pow_mod(252533, n - 1, 33554393)) % 33554393