50 lines
1.5 KiB
Python
50 lines
1.5 KiB
Python
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"""
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--- Part Two ---
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Your device's communication system is correctly detecting packets, but
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still isn't working. It looks like it also needs to look for messages.
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A start-of-message marker is just like a start-of-packet marker, except
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it consists of 14 distinct characters rather than 4.
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Here are the first positions of start-of-message markers for all of the
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above examples:
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mjqjpqmgbljsphdztnvjfqwrcgsmlb: first marker after character 19
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bvwbjplbgvbhsrlpgdmjqwftvncz: first marker after character 23
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nppdvjthqldpwncqszvftbrmjlhg: first marker after character 23
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nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg: first marker after character 29
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zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw: first marker after character 26
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How many characters need to be processed before the first
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start-of-message marker is detected?
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"""
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def main():
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with open("input.txt", "r", encoding="utf-8") as input_file:
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data_stream = input_file.read()
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read_chars = []
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for index, char in enumerate(data_stream):
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read_chars.append(char)
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# We need 14 unique characters, so as long as less than 14 chars
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# were read, just continue loading characters.
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if len(read_chars) < 14:
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continue
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# We only need the last 4 characters to compare, so if we load
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# a fifth char we can pop the oldest out of the list.
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if len(read_chars) == 15:
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read_chars.pop(0)
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if len(set(read_chars)) == 14:
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print(f"After {index+1} chars")
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break
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if __name__ == "__main__":
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main()
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