100 lines
3.2 KiB
Plaintext
100 lines
3.2 KiB
Plaintext
Advent of Code
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--- Day 7: Some Assembly Required ---
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This year, Santa brought little Bobby Tables a set of wires and bitwise
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logic gates! Unfortunately, little Bobby is a little under the recommended
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age range, and he needs help assembling the circuit.
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Each wire has an identifier (some lowercase letters) and can carry a 16-bit
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signal (a number from 0 to 65535). A signal is provided to each wire by a
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gate, another wire, or some specific value. Each wire can only get a signal
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from one source, but can provide its signal to multiple destinations. A gate
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provides no signal until all of its inputs have a signal.
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The included instructions booklet describes how to connect the parts
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together: x AND y -> z means to connect wires x and y to an AND gate, and
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then connect its output to wire z.
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For example:
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• 123 -> x means that the signal 123 is provided to wire x.
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• x AND y -> z means that the bitwise AND of wire x and wire y is provided
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to wire z.
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• p LSHIFT 2 -> q means that the value from wire p is left-shifted by 2
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and then provided to wire q.
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• NOT e -> f means that the bitwise complement of the value from wire e is
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provided to wire f.
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Other possible gates include OR (bitwise OR) and RSHIFT (right-shift). If,
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for some reason, you'd like to emulate the circuit instead, almost all
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programming languages (for example, C, JavaScript, or Python) provide
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operators for these gates.
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For example, here is a simple circuit:
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123 -> x
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456 -> y
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x AND y -> d
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x OR y -> e
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x LSHIFT 2 -> f
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y RSHIFT 2 -> g
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NOT x -> h
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NOT y -> i
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After it is run, these are the signals on the wires:
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d: 72
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e: 507
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f: 492
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g: 114
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h: 65412
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i: 65079
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x: 123
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y: 456
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In little Bobby's kit's instructions booklet (provided as your puzzle
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input), what signal is ultimately provided to wire a?
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Your puzzle answer was 16076.
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--- Part Two ---
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Now, take the signal you got on wire a, override wire b to that signal, and
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reset the other wires (including wire a). What new signal is ultimately
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provided to wire a?
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Your puzzle answer was 2797.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should return to your advent calendar and try another
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puzzle.
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If you still want to see it, you can get your puzzle input.
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References
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Visible links
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. http://adventofcode.com/
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. http://adventofcode.com/about
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. http://adventofcode.com/stats
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. http://adventofcode.com/leaderboard
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. http://adventofcode.com/settings
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. http://adventofcode.com/auth/logout
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. https://en.wikipedia.org/wiki/Bitwise_operation
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. https://en.wikipedia.org/wiki/16-bit
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. https://en.wikipedia.org/wiki/Bitwise_operation#AND
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. https://en.wikipedia.org/wiki/Logical_shift
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. https://en.wikipedia.org/wiki/Bitwise_operation#NOT
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. https://en.wikipedia.org/wiki/Bitwise_operation#OR
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. https://en.wikipedia.org/wiki/Logical_shift
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. https://en.wikipedia.org/wiki/Bitwise_operations_in_C
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. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators
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. https://wiki.python.org/moin/BitwiseOperators
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. http://adventofcode.com/
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. http://adventofcode.com/day/7/input
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