with open('day17-input', 'r') as file: data = [l.strip('\n') for l in file] import numpy as np import re Xmin = [int(re.findall(r'x=(\d+)', d)[0]) for d in data] Xmax = [int(re.findall(r'x=(?:\d+\.\.)?(\d+)', d)[0]) for d in data] Ymin = [int(re.findall(r'y=(\d+)', d)[0]) for d in data] Ymax = [int(re.findall(r'y=(?:\d+\.\.)?(\d+)', d)[0]) for d in data] y_min = min(Ymin) y_max = max(Ymax) x_min = min(Xmin) - 1 x_max = 700 - x_min init_grid = np.zeros((x_max, y_max+1), dtype=np.int64) # 0 = Sand, 1 = Clay, 2 = water, -1 = running water spring = (500-x_min, 0) for xmin, xmax, ymin, ymax in zip(Xmin, Xmax, Ymin, Ymax): init_grid[xmin-x_min:xmax+1-x_min, ymin:ymax+1] = 1 grid = init_grid.copy() drop_point_blacklist = set() # Cliff drop-offs that are guaranteed to go nowhere def drop_water(source=spring): if tuple(source) in drop_point_blacklist: return False x, y = source surface = (grid[x, y:] > 0).argmax() if surface == 0: if (grid[x, y-1:] > 0).argmax() == 0: grid[x, y:] = -1 drop_point_blacklist.add(tuple(source)) return False surface_y = surface + y grid[x, y:surface_y] = -1 # Find walls left and right wall_left = (grid[x:0:-1, surface_y-1] > 0).argmax() wall_right = (grid[x:, surface_y-1] > 0).argmax() if wall_left: left_x = x - wall_left + 1 cliff = (grid[x:left_x-1:-1, surface_y] <= 0).argmax() if cliff: wall_left = False if wall_right: right_x = x + wall_right #- 1 cliff = (grid[x:right_x, surface_y] <= 0).argmax() if cliff: wall_right = False if wall_right and wall_left: # Fill level of basin grid[left_x:right_x, surface_y-1] = 2 return True cliffs = set() if not wall_left: cliff = int((grid[x:0:-1, surface_y] <= 0).argmax()) grid[x-cliff:x, surface_y-1] = -1 if wall_right: grid[x:right_x, surface_y - 1] = -1 if cliff: cliffs.add((x - cliff, surface_y)) if not wall_right: cliff = int((grid[x:, surface_y] <= 0).argmax()) grid[x:x+cliff+1, surface_y-1] = -1 if wall_left: grid[left_x:x, surface_y-1] = -1 if cliff: cliffs.add((x + cliff, surface_y)) if cliffs and len([c for c in cliffs if tuple(c) in drop_point_blacklist]) == len(cliffs): # We go to 1 or 2 cliffs, all of which are dead-ends. We are a dead end, stop looking at us. drop_point_blacklist.add(tuple(source)) return False succeeded = False while sum([drop_water(c) for c in cliffs]): succeeded = True return succeeded def visualize(): vis_rows = [] for row in range(y_max+1): vis_rows.append(''.join([('.', '#', '~', '|')[grid[col, row]] for col in range(x_max)])) with open('day17-vis', 'w') as file: file.write('\n'.join(vis_rows)) while drop_water(): pass print((grid==2).sum() + (grid==-1).sum() - y_min) # Part 1 print((grid==2).sum()) # Part 2 visualize()