My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add naive BFS solution for 2016/11
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2016/day11.py
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2016/day11.py
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import re
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import fileinput
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from itertools import combinations
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def complete(state):
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return all(f == 3 for f in state)
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def valid(state):
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gens = set(state[::2])
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for i, floor in enumerate(state):
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# Element is a chip if it has an odd index
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if i % 2 == 1:
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# Its matching generator is on the same floor, so it's fine
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if state[i-1] == floor:
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continue
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# There is another generator on the floor
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if floor in gens:
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return False
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return True
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def solve(state, start_floor=0):
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if start_floor == 3 and complete(state):
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return 0
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horizon = [(start_floor, state)]
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steps = 0
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seen = set()
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while horizon:
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new_horizon = []
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for floor, state in horizon:
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can_move = [i for i, f in enumerate(state) if f == floor]
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moves = []
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if floor < 3:
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moves.extend([(2, floor + 1), (1, floor + 1)])
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if floor > 0:
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moves.extend([(1, floor - 1), (2, floor - 1)])
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moved_two_up = False
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moved_one_down = False
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for n, new_floor in moves:
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# Don't move one item up if you can move two,
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# and don't move two items down if can move one
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if n == 1 and new_floor > floor and moved_two_up:
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continue
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elif n == 2 and new_floor < floor and moved_one_down:
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continue
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for move in combinations(can_move, n):
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next_state = tuple(new_floor if i in move else f for i, f in enumerate(state))
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if complete(next_state):
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return steps + 1
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if valid(next_state) and (new_floor, next_state) not in seen:
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pair = (new_floor, next_state)
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new_horizon.append(pair)
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seen.add(pair)
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if n == 2 and new_floor > floor:
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moved_two_up = True
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if n == 1 and new_floor < floor:
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moved_one_down = True
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horizon = new_horizon
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steps += 1
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generators = {}
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microchips = {}
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for i, line in enumerate(fileinput.input()):
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for gen in re.findall(r'(\w+) generator', line):
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generators[gen] = i
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for chip in re.findall(r'(\w+)-compatible microchip', line):
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microchips[chip] = i
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STATE = []
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for key in generators:
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STATE.append(generators[key])
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STATE.append(microchips[key])
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STATE = tuple(STATE)
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print "Minimum number of steps:", solve(STATE)
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STATE = tuple(list(STATE) + [0, 0, 0, 0])
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print "With four new objects:", solve(STATE)