75 lines
3.3 KiB
Plaintext
75 lines
3.3 KiB
Plaintext
|
Advent of Code
|
|||
|
|
|||
|
--- Day 25: Clock Signal ---
|
|||
|
|
|||
|
You open the door and find yourself on the roof. The city sprawls away from you for miles and miles.
|
|||
|
|
|||
|
There's not much time now - it's already Christmas, but you're nowhere near the North Pole, much too far to deliver
|
|||
|
these stars to the sleigh in time.
|
|||
|
|
|||
|
However, maybe the huge antenna up here can offer a solution. After all, the sleigh doesn't need the stars, exactly; it
|
|||
|
needs the timing data they provide, and you happen to have a massive signal generator right here.
|
|||
|
|
|||
|
You connect the stars you have to your prototype computer, connect that to the antenna, and begin the transmission.
|
|||
|
|
|||
|
Nothing happens.
|
|||
|
|
|||
|
You call the service number printed on the side of the antenna and quickly explain the situation. "I'm not sure what
|
|||
|
kind of equipment you have connected over there," he says, "but you need a clock signal." You try to explain that this
|
|||
|
is a signal for a clock.
|
|||
|
|
|||
|
"No, no, a clock signal - timing information so the antenna computer knows how to read the data you're sending it. An
|
|||
|
endless, alternating pattern of 0, 1, 0, 1, 0, 1, 0, 1, 0, 1...." He trails off.
|
|||
|
|
|||
|
You ask if the antenna can handle a clock signal at the frequency you would need to use for the data from the stars.
|
|||
|
"There's no way it can! The only antenna we've installed capable of that is on top of a top-secret Easter Bunny
|
|||
|
installation, and you're definitely not-" You hang up the phone.
|
|||
|
|
|||
|
You've extracted the antenna's clock signal generation assembunny code (your puzzle input); it looks mostly compatible
|
|||
|
with code you worked on just recently.
|
|||
|
|
|||
|
This antenna code, being a signal generator, uses one extra instruction:
|
|||
|
|
|||
|
• out x transmits x (either an integer or the value of a register) as the next value for the clock signal.
|
|||
|
|
|||
|
The code takes a value (via register a) that describes the signal to generate, but you're not sure how it's used. You'll
|
|||
|
have to find the input to produce the right signal through experimentation.
|
|||
|
|
|||
|
What is the lowest positive integer that can be used to initialize register a and cause the code to output a clock
|
|||
|
signal of 0, 1, 0, 1... repeating forever?
|
|||
|
|
|||
|
Your puzzle answer was ____.
|
|||
|
|
|||
|
--- Part Two ---
|
|||
|
|
|||
|
The antenna is ready. Now, all you need is the fifty stars required to generate the signal for the sleigh, but you don't
|
|||
|
have enough.
|
|||
|
|
|||
|
You look toward the sky in desperation... suddenly noticing that a lone star has been installed at the top of the
|
|||
|
antenna! Only 49 more to go.
|
|||
|
|
|||
|
If you like, you can [ [Retransmit the Signal] ] .
|
|||
|
|
|||
|
Both parts of this puzzle are complete! They provide two gold stars: **
|
|||
|
|
|||
|
References
|
|||
|
|
|||
|
Visible links
|
|||
|
. http://adventofcode.com/
|
|||
|
. http://adventofcode.com/2016/about
|
|||
|
. http://adventofcode.com/2016/support
|
|||
|
. http://adventofcode.com/2016/events
|
|||
|
. http://adventofcode.com/2016/settings
|
|||
|
. http://adventofcode.com/2016/auth/logout
|
|||
|
. http://adventofcode.com/2016
|
|||
|
. http://adventofcode.com/2016
|
|||
|
. http://adventofcode.com/2016/leaderboard
|
|||
|
. http://adventofcode.com/2016/stats
|
|||
|
. http://adventofcode.com/2016/sponsors
|
|||
|
. http://adventofcode.com/2016/sponsors
|
|||
|
. https://en.wikipedia.org/wiki/Clock_signal
|
|||
|
. http://adventofcode.com/2016/day/12
|
|||
|
. http://adventofcode.com/2016/day/23
|
|||
|
. http://adventofcode.com/2016
|
|||
|
. http://adventofcode.com/2016/day/25/input
|