As I did with last year / yesterday, I’ve written up a series of posts for the Advent of Code 2017 problems. Again, I didn’t manage to write them up as I did them, but this time around I least I finished mostly on time.
As I did with last year / yesterday, I’ve written up a series of posts for the Advent of Code 2017 problems. Again, I didn’t manage to write them up as I did them, but this time around I least I finished mostly on time.
Part 1: Implement a Turing machine defined as such:
Begin in state A. Perform a diagnostic checksum after 6 steps.
In state A: If the current value is 0:  Write the value 1.  Move one slot to the right.  Continue with state B. If the current value is 1:  Write the value 0.  Move one slot to the left.  Continue with state B.
…
Part 1: Given a series of reversible components of the form
3/4
(can connect a3
on one end to a4
on the other), form a bridge of components. The bridge’s strength is equal to the sum of component values. So0/3, 3/7, and 7/4
has a strength of0+3 + 3+7 + 7+4 = 24
.
What is the strongest possible bridge?
Part 1: Create a variation of the previous DuetVM with only the following four instructions:
set X Y
sets registerX
toY
sub X Y
set registerX
toX  Y
mul X Y
sets registerX
toX * Y
jnz X Y
jumps with an offset of the value ofY
, iffX
is not equal to zero
If you run the given program, how many times is
mul
invoked?
Part 1: Implement a cellular automaton on an infinite grid of
.
and#
pixels such that:
 Start at
(0, 0)
, facingUp
 Repeat:
 If the cursor is on
.
swap it to#
and turnLeft
 If the cursor is on
#
swap it to.
and turnRight
 Either way, after turning, move forward once
After 10,000 iterations, how many pixels were turned from
.
to#
?
Part 1: Start with an input image made of
.
and#
pixels. Forn
iterations, break the image into blocks:
 If the current size is even, break the image into 2x2 chunks and replace each with a 3x3 chunk
 If the current size is odd, break the image into 3x3 chunks and replace each with a 4x4 chunk
The replacement rules will be specified in the following format (example is a 3x3 > 4x4 rule):
.#./..#/### => #..#/…./…./#..#
> In that example, replace this:
> ```
.#.
..#
###
With this:
#..# …. …. #..#
Part 1: Given the initial position, velocity, and acceleration of a large number of particles, which particle will stay the closet to the origin as the simulation runs to infinity?
Part 1: Take a network diagram of the following form:

 ++
A  C
F—–E—+    D +B+ +–+
Part 1: Create a virtual machine with the following instruction set:
snd X
plays a sound with a frequency equal to the value ofX
set X Y
sets registerX
toY
add X Y
set registerX
toX + Y
mul X Y
sets registerX
toX * Y
mod X Y
sets registerX
toX mod Y
rcv X
recovers the frequency of the last sound played, ifX
is not zerojgz X Y
jumps with an offset of the value ofY
, iffX
is greater than zero
In most cases,
X
andY
can be either an integer value or a register.
What is the value recovered by
rcv
the first timeX
is nonzero?
Part 1: Start with a circular buffer containing
[0]
andcurrent_position = 0
. Forn
from1
up to2017
:
 Step forward
steps
(puzzle input) Input the next value for
n
, setcurrent_position
ton
, incrementn
 Repeat
What is the value after 2017?
It’s a bit weird to describe, but the given example helps (assume steps = 3
):
(0)
0 (1)
0 (2) 1
0 2 (3) 1
0 2 (4) 3 1
0 (5) 2 4 3 1
0 5 2 4 3 (6) 1
0 5 (7) 2 4 3 6 1
0 5 7 2 4 3 (8) 6 1
0 (9) 5 7 2 4 3 8 6 1