21 lines
1.2 KiB
Plaintext
21 lines
1.2 KiB
Plaintext
--- Part Two ---
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You notice that the device repeats the same frequency change list over and over. To calibrate the device, you need to find the first frequency it reaches twice.
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For example, using the same list of changes above, the device would loop as follows:
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Current frequency 0, change of +1; resulting frequency 1.
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Current frequency 1, change of -2; resulting frequency -1.
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Current frequency -1, change of +3; resulting frequency 2.
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Current frequency 2, change of +1; resulting frequency 3.
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(At this point, the device continues from the start of the list.)
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Current frequency 3, change of +1; resulting frequency 4.
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Current frequency 4, change of -2; resulting frequency 2, which has already been seen.
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In this example, the first frequency reached twice is 2. Note that your device might need to repeat its list of frequency changes many times before a duplicate frequency is found, and that duplicates might be found while in the middle of processing the list.
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Here are other examples:
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+1, -1 first reaches 0 twice.
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+3, +3, +4, -2, -4 first reaches 10 twice.
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-6, +3, +8, +5, -6 first reaches 5 twice.
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+7, +7, -2, -7, -4 first reaches 14 twice.
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What is the first frequency your device reaches twice? |