Advent of Code

--- Day 7: Some Assembly Required ---

   This year, Santa brought little Bobby Tables a set of wires and bitwise
   logic gates! Unfortunately, little Bobby is a little under the recommended
   age range, and he needs help assembling the circuit.

   Each wire has an identifier (some lowercase letters) and can carry a 16-bit
   signal (a number from 0 to 65535). A signal is provided to each wire by a
   gate, another wire, or some specific value. Each wire can only get a signal
   from one source, but can provide its signal to multiple destinations. A gate
   provides no signal until all of its inputs have a signal.

   The included instructions booklet describes how to connect the parts
   together: x AND y -> z means to connect wires x and y to an AND gate, and
   then connect its output to wire z.

   For example:

     • 123 -> x means that the signal 123 is provided to wire x.

     • x AND y -> z means that the bitwise AND of wire x and wire y is provided
       to wire z.

     • p LSHIFT 2 -> q means that the value from wire p is left-shifted by 2
       and then provided to wire q.

     • NOT e -> f means that the bitwise complement of the value from wire e is
       provided to wire f.

   Other possible gates include OR (bitwise OR) and RSHIFT (right-shift). If,
   for some reason, you'd like to emulate the circuit instead, almost all
   programming languages (for example, C, JavaScript, or Python) provide
   operators for these gates.

   For example, here is a simple circuit:

 123 -> x
 456 -> y
 x AND y -> d
 x OR y -> e
 x LSHIFT 2 -> f
 y RSHIFT 2 -> g
 NOT x -> h
 NOT y -> i

   After it is run, these are the signals on the wires:

 d: 72
 e: 507
 f: 492
 g: 114
 h: 65412
 i: 65079
 x: 123
 y: 456

   In little Bobby's kit's instructions booklet (provided as your puzzle
   input), what signal is ultimately provided to wire a?

   Your puzzle answer was 16076.

--- Part Two ---

   Now, take the signal you got on wire a, override wire b to that signal, and
   reset the other wires (including wire a). What new signal is ultimately
   provided to wire a?

   Your puzzle answer was 2797.

   Both parts of this puzzle are complete! They provide two gold stars: **

   At this point, you should return to your advent calendar and try another
   puzzle.

   If you still want to see it, you can get your puzzle input.

References

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   . https://en.wikipedia.org/wiki/Bitwise_operation
   . https://en.wikipedia.org/wiki/16-bit
   . https://en.wikipedia.org/wiki/Bitwise_operation#AND
   . https://en.wikipedia.org/wiki/Logical_shift
   . https://en.wikipedia.org/wiki/Bitwise_operation#NOT
   . https://en.wikipedia.org/wiki/Bitwise_operation#OR
   . https://en.wikipedia.org/wiki/Logical_shift
   . https://en.wikipedia.org/wiki/Bitwise_operations_in_C
   . https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators
   . https://wiki.python.org/moin/BitwiseOperators
   . http://adventofcode.com/
   . http://adventofcode.com/day/7/input
