312 lines
8.7 KiB
Python
312 lines
8.7 KiB
Python
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#!/bin/python3
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from enum import Enum
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from collections import defaultdict
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from itertools import pairwise, combinations
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class Move(Enum):
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LEFT = 1
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RIGHT = 2
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DOWN = 3
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moves = list()
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with open('inputs/day17.txt', 'r') as f:
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for line in f:
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for char in line.strip():
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if char == '<':
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moves.append(Move.LEFT)
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elif char == '>':
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moves.append(Move.RIGHT)
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def move_stream():
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while True:
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for i, d in enumerate(moves):
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yield (i, d)
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yield (i, Move.DOWN)
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move_map = {Move.LEFT: (-1, 0), Move.RIGHT: (1, 0), Move.DOWN: (0, -1)}
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class Rock():
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def __init__(self, shape):
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self.blocks = shape
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def init_position(self, y_top):
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self.blocks = list(map(lambda pos: (pos[0] + 2, pos[1] + y_top + 4), self.blocks))
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def move(self, chamber, move):
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new_blocks = self.move_blocks(move)
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if self.check_valid(chamber, new_blocks):
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self.blocks = new_blocks
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return True
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else:
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return False
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def move_blocks(self, move):
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(movex, movey) = move_map[move]
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return list(map(lambda block: (block[0] + movex, block[1] + movey), self.blocks))
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def check_valid(self, chamber, blocks):
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for (x, y) in blocks:
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if x > 6 or x < 0 or chamber[y][x]:
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return False
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return True
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shapes = [
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[(0, 0), (1, 0), (2, 0), (3, 0)],
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[(0, 1), (1, 1), (2, 1), (1, 0), (1, 2)],
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[(0, 0), (1, 0), (2, 0), (2, 1), (2, 2)],
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[(0, 0), (0, 1), (0, 2), (0, 3)],
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[(0, 0), (1, 0), (0, 1), (1, 1)]
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]
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def rock_stream():
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while True:
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for i, shape in enumerate(shapes):
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yield (i, Rock(shape.copy()))
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chamber = defaultdict(lambda: defaultdict(lambda: False))
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for i in range(7):
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chamber[-1][i] = True
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def print_chamber(chamber, rock, print_index):
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keys = list(reversed(sorted(chamber.keys())))
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for key in keys:
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if print_index:
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print(f'{key}\t', end='')
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for i in range(7):
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if chamber[key][i]:
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print('#', end='')
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elif rock and (i, key) in rock.blocks:
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print('@', end='')
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else:
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print('.', end='')
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print('')
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def prune_chamber(chamber):
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ys = list(reversed(sorted(chamber.keys())))
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prune_height = None
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for y_high, y_low in pairwise(ys):
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prunable = True
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for x in range(7):
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if not chamber[y_high][x] and not chamber[y_low][x]:
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prunable = False
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break
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if prunable:
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prune_height = y_low
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break
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if prune_height:
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for y in ys:
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if y < prune_height:
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del chamber[y]
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return prune_height != None
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def row_to_mask(row):
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mask = 0
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bit = 1
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for x in range(6, -1, -1):
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if row[x]:
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mask = mask | bit
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bit = bit << 1
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return mask
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barrier_fingerprints = defaultdict(lambda: list())
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rock_count = 20220
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prune_freq = 100
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y_top = -1
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moves_gen = move_stream()
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rocks_gen = rock_stream()
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rocks_fallen = 0
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rock_idx = None
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for rock_idx, rock in rocks_gen:
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rock.init_position(y_top)
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for move_idx, move in moves_gen:
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moved = rock.move(chamber, move)
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if not moved and move == Move.DOWN:
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for (x, y) in rock.blocks:
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if y > y_top:
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y_top = y
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chamber[y][x] = True
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rocks_fallen += 1
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break
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ys = set(map(lambda x: x[1], rock.blocks))
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for y in ys:
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all_filled = True
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for x in range(7):
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if not chamber[y][x] and not chamber[y-1][x]:
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all_filled = False
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break
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if all_filled:
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mask_high = row_to_mask(chamber[y])
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mask_low = row_to_mask(chamber[y-1])
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fingerprint = (rock_idx, move_idx, mask_high, mask_low)
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barrier_fingerprints[fingerprint].append((rocks_fallen, y))
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if rocks_fallen == rock_count:
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break
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print('part1', y_top + 1)
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candidate_fp = None
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candidate_ys_count = 0
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for fp, ys in barrier_fingerprints.items():
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l = len(ys)
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if l > candidate_ys_count:
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candidate_ys_count = l
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candidate_fp = fp
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# print('candidate FP:', candidate_fp)
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first_occ = barrier_fingerprints[candidate_fp][0]
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second_occ = barrier_fingerprints[candidate_fp][1]
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height_cycle = second_occ[1] - first_occ[1]
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rock_cycle = second_occ[0] - first_occ[0]
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# print('first occurance:', 'height', first_occ[1], 'fallen', first_occ[0])
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# print('second occurance:', 'height', second_occ[1], 'fallen', second_occ[0])
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# print('height cycle:', second_occ[1] - first_occ[1])
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# print('rock cycle:', second_occ[0] - first_occ[0])
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rocks_left = 1000000000000 - first_occ[0]
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superheight = first_occ[1]
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superheight += (rocks_left // rock_cycle) * height_cycle
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rocks_left %= rock_cycle
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print(rocks_left, superheight)
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# We just need $rocks_left rocks more!
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# Move to the next cycle point
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# Then simulate $rocks_left movements to get the height this generates.
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# Add this to superheight then subtract one height_cycle.
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for rock_idx, rock in rocks_gen:
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rock.init_position(y_top)
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for move_idx, move in moves_gen:
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moved = rock.move(chamber, move)
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if not moved and move == Move.DOWN:
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for (x, y) in rock.blocks:
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if y > y_top:
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y_top = y
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chamber[y][x] = True
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rocks_fallen += 1
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break
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ys = set(map(lambda x: x[1], rock.blocks))
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cycle_start = False
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for y in ys:
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all_filled = True
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for x in range(7):
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if not chamber[y][x] and not chamber[y-1][x]:
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all_filled = False
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break
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if all_filled:
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mask_high = row_to_mask(chamber[y])
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mask_low = row_to_mask(chamber[y-1])
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fingerprint = (rock_idx, move_idx, mask_high, mask_low)
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if fingerprint == candidate_fp:
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cycle_start = True
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break
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if cycle_start:
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break
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start_height = y_top
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for rock_idx, rock in rocks_gen:
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rock.init_position(y_top)
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for move_idx, move in moves_gen:
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moved = rock.move(chamber, move)
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if not moved and move == Move.DOWN:
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for (x, y) in rock.blocks:
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if y > y_top:
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y_top = y
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chamber[y][x] = True
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rocks_left -= 1
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break
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if rocks_left == 0:
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break
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end_height = y_top
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superheight += end_height - start_height
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print('part2', superheight + 3)
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# for fp, ys in barrier_fingerprints.items():
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# print('fingerprint:', fp)
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# print('count:', len(ys))
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# NEW IDEA
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# Find a cycle.
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# A cycle can be characterized by: rock rotation, direction rotation and rock formation.
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# Problem is, we need to save a lot of the rock formation, because new rocks can fall down a long while.
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# Additionally, we cannot just save the height of each column, because rocks can move underneath hanging arches.
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# Possible solution: find lines that block this.
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# Possibly in one line, definitely in two lines.
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# IDEA:
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# Create bitmap.
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# Easily compare bitmaps with eachother to find cycle
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# def print_mask(mask):
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# bit = 1 << 6
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# for i in range(7):
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# if mask & (bit >> i):
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# print('1', end='')
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# else:
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# print('0', end='')
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# print('')
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# def print_bitmap(bitmap):
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# for row in bitmap:
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# print_mask(row)
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# bitmap = []
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# ys = list(reversed(sorted(chamber.keys())))
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# y_min = min(ys)
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# y_max = max(ys)
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# for y in range(y_min + 1, y_max + 1):
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# mask = 0
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# bit = 1
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# for x in range(6, -1, -1):
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# if chamber[y][x]:
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# mask = mask | bit
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# bit = bit << 1
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# print_mask(mask)
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# bitmap.append(mask)
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# def in_order(l):
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# last = None
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# for x in l:
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# if last == None or x > last:
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# last = x
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# else:
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# return False
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# return True
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# def same_distance(l):
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# [y1, y2, y3] = l
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# return y2 - y1 == y3 - y2
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# def is_cycle(bitmap, l):
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# [y1, y2, y3] = l
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# distance = y3 - y2
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# for i in range(distance + 1):
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# if bitmap[y1+i] != bitmap[y2]+i:
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# return False
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# return True
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# Now try to find the cycle!
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# We loop over every row.
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# We find all indices of this row in the whole chamber
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# checked = []
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# print('finding cycle')
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# for row in bitmap:
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# print('row:', row)
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# if row not in checked:
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# checked.append(row)
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# indices = [i for i, x in enumerate(bitmap) if x == row]
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# if len(indices) >= 3:
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# for maybe_cycle in combinations(indices, 3):
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# if in_order(maybe_cycle) and same_distance(maybe_cycle):
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# if is_cycle(bitmap, maybe_cycle):
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# print('FOUND CYCLE:', maybe_cycle)
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# # print_bitmap(bitmap)
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