#!/usr/bin/env python import sys from typing import Iterator, List, Tuple HeightMap = List[List[int]] Point = Tuple[int, int] def solve(input: List[str]) -> int: height_map = [[int(c) for c in line] for line in input] def neighbours_of(point: Point) -> Iterator[Point]: for dx, dy in (-1, 0), (1, 0), (0, -1), (0, 1): x, y = point[0] + dx, point[1] + dy if x < 0 or x >= len(height_map): continue if y < 0 or y >= len(height_map[0]): continue yield x, y def is_low_point(point: Point) -> bool: for neighbour in neighbours_of(point): if height_map[neighbour[0]][neighbour[1]] <= height_map[point[0]][point[1]]: return False return True def explore_bassin(point: Point) -> int: to_be_seen = set(neighbours_of(point)) explored = {point} bassin = {point} while len(to_be_seen) > 0: new = to_be_seen.pop() explored.add(new) if height_map[new[0]][new[1]] == 9: continue bassin.add(new) for neighbour in neighbours_of(new): if neighbour in explored: continue to_be_seen.add(neighbour) return len(bassin) points = [(x, y) for x in range(len(height_map)) for y in range(len(height_map[0]))] low_points = filter(is_low_point, points) bassin_sizes = sorted(map(explore_bassin, low_points), reverse=True) return bassin_sizes[0] * bassin_sizes[1] * bassin_sizes[2] def main() -> None: input = [line.strip() for line in sys.stdin.readlines()] print(solve(input)) if __name__ == "__main__": main()