123 lines
2.7 KiB
Python
123 lines
2.7 KiB
Python
import sys
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from math import prod
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LITERAL = 4
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OPERATOR = {
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0: sum,
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1: prod,
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2: min,
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3: max,
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5: lambda lst: int(lst[0] > lst[1]),
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6: lambda lst: int(lst[0] < lst[1]),
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7: lambda lst: int(lst[0] == lst[1]),
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}
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total_version = 0
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def read_bits(bits, start, n) -> tuple[str, int]:
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end = start + n
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return bits[start:end], end
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def read_bits_int(bits, start, n) -> tuple[int, int]:
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number_bits, pos = read_bits(bits, start, n)
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return int(number_bits, base=2), pos
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def hex_to_bits(hex: str) -> str:
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return format(int(hex, base=16), "04b")
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def hex_string_to_bit_string(hex_string: str) -> str:
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return "".join([hex_to_bits(x) for x in list(hex_string)])
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def parse_packet(bits) -> int:
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pos = 0
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packet_version, _ = read_bits_int(bits, pos, 3)
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global total_version
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total_version += packet_version
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type_ID, _ = read_bits_int(bits[3:], pos, 3)
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if type_ID == LITERAL:
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# print("Found: literal")
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value, next_pos = parse_literal(bits[pos:])
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# print("literal:", value)
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else:
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# print("found: operator")
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value, next_pos = parse_operator(bits[pos:])
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pos += next_pos
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return value, pos
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def parse_literal(bits) -> tuple[int, int]:
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pos = 0
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packet_version, pos = read_bits_int(bits, pos, 3)
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type_ID, pos = read_bits_int(bits, pos, 3)
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number = ""
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done = False
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while not done:
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part, pos = read_bits(bits, pos, 5)
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if part[0] == "0":
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done = True
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number += part[1:]
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return int(number, base=2), pos
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def parse_operator(bits) -> int:
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pos = 0
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packet_version, pos = read_bits_int(bits, pos, 3)
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type_ID, pos = read_bits_int(bits, pos, 3)
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length_type_id = bits[6]
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pos = 7
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parts = []
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if length_type_id == "0":
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total_length, pos = read_bits_int(bits, pos, 15)
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# print("total length:", total_length)
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read = 0
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while read != total_length:
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value, just_read = parse_packet(bits[pos:])
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read += just_read
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# print(f"Length was: {just_read}, total: {read} of {total_length}")
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pos += just_read
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parts.append(value)
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else:
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number_of_subs, pos = read_bits_int(bits, pos, 11)
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# print("number of subs:", number_of_subs)
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for i in range(number_of_subs):
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value, next_pos = parse_packet(bits[pos:])
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parts.append(value)
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pos += next_pos
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calculated = OPERATOR[type_ID](parts)
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return calculated, pos
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if __name__ == "__main__":
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hex_string = sys.stdin.readline().strip()
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bits = hex_string_to_bit_string(hex_string)
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value, _ = parse_operator(bits)
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print("part one:", total_version)
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print("part two:", value)
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