70 lines
1.9 KiB
Python
70 lines
1.9 KiB
Python
#! /usr/bin/env python3
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from itertools import product
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from bisect import bisect
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def main(filename):
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results = {}
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with open(filename) as inp:
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for line in inp:
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boarding_pass = line.rstrip()
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row, col = parse_boarding_pass(boarding_pass)
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seat_id = get_seat_id(row, col)
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results[boarding_pass] = (row, col, seat_id)
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part1(results)
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part2(results)
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def part1(results):
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# part 1
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max_seat_id = max(x[2] for x in results.values())
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print("Max seat ID: ", max_seat_id)
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def part2(results):
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seat_ids = sorted(x[2] for x in results.values())
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missing_seat_ids = set(range(max(seat_ids))) - set(seat_ids)
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print("Your seat id : ", max(missing_seat_ids))
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def parse_boarding_pass(boarding_pass, strategy="binary"):
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"Poor man's dispatcher"
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try:
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to_call = globals()[f"parse_boarding_pass_{strategy}"]
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return to_call(boarding_pass)
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except KeyError:
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raise KeyError(f"Bad strategy name {strategy}")
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def parse_boarding_pass_binary(boarding_pass):
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"Parse boarding pass using a binary conversion"
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boarding_pass = boarding_pass.translate(str.maketrans("FLBR", "0011"))
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row = boarding_pass[:7]
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col = boarding_pass[7:]
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return int(row, base=2), int(col, base=2)
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def parse_boarding_pass_bisect(boarding_pass):
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"Pass boarding pass using bisection algorithm"
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row = bisect(boarding_pass[:7], lower_option="F", upper_option="B", max=127)
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col = bisect(boarding_pass[7:], lower_option="L", upper_option="R", max=7)
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return row, col
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def bisect(inp, lower_option, upper_option, max):
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min_v, max_v = 0, max
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for l in inp:
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length = max_v - min_v
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if l == lower_option:
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max_v = min_v + length // 2
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elif l == upper_option:
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min_v = 1 + min_v + length // 2
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return min_v
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def get_seat_id(row, col):
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return 8 * row + col
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if __name__ == "__main__":
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main('input.txt')
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