22!
spoilers!
Well it’s not a grid! My chosen language does not have bitwise operators so it’s a bit slow. Have to resort to manual parallelization.
22!
spoilers!
Well it’s not a grid! My chosen language does not have bitwise operators so it’s a bit slow. Have to resort to manual parallelization.
EDIT: I have a sneaking suspicion that the computer will need to be re-used since the combo-operand 7 does not occur and is "reserved".
re p2
Also did this by hand to get my precious gold star, but then actually went back and implemented it
Some JQ extension required:
#!/usr/bin/env jq -n -rR -f
#─────────── Big-endian to_bits and from_bits ────────────#
def to_bits:
if . == 0 then [0] else { a: ., b: [] } | until (.a == 0;
.a /= 2 |
if .a == (.a|floor) then .b += [0]
else .b += [1] end | .a |= floor
) | .b end;
def from_bits:
{ a: 0, b: ., l: length, i: 0 } | until (.i == .l;
.a += .b[.i] * pow(2;.i) | .i += 1
) | .a;
#──────────── Big-endian xor returns integer ─────────────#
def xor(a;b): [a, b] | transpose | map(add%2) | from_bits ;
[ inputs | scan("\\d+") | tonumber ] | .[3:] |= [.]
| . as [$A,$B,$C,$pgrm] |
# Assert #
if [first(
range(8) as $x |
range(8) as $y |
range(8) as $_ |
[
[2,4], # B = A mod 8 # Zi
[1,$x], # B = B xor x # = A[i*3:][0:3] xor x
[7,5], # C = A << B (w/ B < 8) # = A(i*3;3) xor x
[1,$y], # B = B xor y # Out[i]
[0,3], # A << 3 # = A(i*3+Zi;3) xor y
[4,$_], # B = B xor C # xor Zi
[5,5], # Output B mod 8 #
[3,0] # Loop while A > 0 # A(i*3;3) = Out[i]
] | select(flatten == $pgrm) # xor A(i*3+Zi;3)
)] == [] # xor constant
then "Reverse-engineering doesn't neccessarily apply!" | halt_error
end |
# When minimizing higher bits first, which should always produce #
# the final part of the program, we can recursively add lower bits #
# Since they are always stricly dependent on a #
# xor of Output x high bits #
def run($A):
# $A is now always a bit array #
# ┌──i is our shift offset for A #
{ p: 0, $A,$B,$C, i: 0} | until ($pgrm[.p] == null;
$pgrm[.p:.p+2] as [$op, $x] | # Op & literal operand
[0,1,2,3,.A,.B,.C,null][$x] as $y | # Op & combo operand
# From analysis all XOR operations can be limited to 3 bits #
# Op == 2 B is only read from A #
# Op == 5 Output is only from B (mod should not be required) #
if $op == 0 then .i += $y
elif $op == 1 then .B = xor(.B|to_bits[0:3]; $x|to_bits[0:3])
elif $op == 2
and $x == 4 then .B = (.A[.i:.i+3] | from_bits)
elif $op == 3
and (.A[.i:]|from_bits) != 0
then .p = ($x - 2)
elif $op == 3 then .
elif $op == 4 then .B = xor(.B|to_bits[0:3]; .C|to_bits[0:3])
elif $op == 5 then .out += [ $y % 8 ]
elif $op == 6 then .B = (.A[.i+$y:][0:3] | from_bits)
elif $op == 7 then .C = (.A[.i+$y:][0:3] | from_bits)
else "Unexpected op and x: \({$op,$x})" | halt_error
end | .p += 2
) | .out;
[ { A: [], i: 0 } | recurse (
# Keep all candidate A that produce the end of the program, #
# since not all will have valid low-bits for earlier parts. #
.A = ([0,1]|combinations(6)) + .A | # Prepend all 6bit combos #
select(run(.A) == $pgrm[-.i*2-2:] ) # Match pgrm from end 2x2 #
| .i += 1
# Keep only the full program matches, and convert back to int #
) | select(.i == ($pgrm|length/2)) | .A | from_bits
]
| min # From all valid self-replicating intputs output the lowest #
Re: p2
Definitely a bit tedious, I had to "play" a whole session to spot bugs that I had. It took me far longer than average. I had buggy dissepearing boxes because of update order, I would reccomend a basic test case of pushing a line/pyramid of boxes in every direction.
Updated Reasoning
Ok it probably works because it isn't bang center but a bit up of center, most other steps most be half half noise vertically, and the reason it doesn;t minimize on an earlier horizontal step (where every step is mostly half half), is because the middle points on the trunk, that don't contribute to the overall product therefore minimizing it even lower.
Day 14, got very lucky on this one, but too tired to think about why part 2 still worked.
spoiler
#!/usr/bin/env jq -n -R -f
# Board size # Our list of robots positions and speed #
[101,103] as [$W,$H] | [ inputs | [scan("-?\\d+")|tonumber] ] |
# Making the assumption that the easter egg occurs when #
# When the quandrant product is minimized #
def sig:
reduce .[] as [$x,$y] ([];
if $x < ($W/2|floor) and $y < ($H/2|floor) then
.[0] += 1
elif $x < ($W/2|floor) and $y > ($H/2|floor) then
.[1] += 1
elif $x > ($W/2|floor) and $y < ($H/2|floor) then
.[2] += 1
elif $x > ($W/2|floor) and $y > ($H/2|floor) then
.[3] += 1
end
) | .[0] * .[1] * .[2] * .[3];
# Only checking for up to W * H seconds #
# There might be more clever things to do, to first check #
# vertical and horizontal alignement separately #
reduce range($W*$H) as $s ({ b: ., bmin: ., min: sig, smin: 0};
.b |= (map(.[2:4] as $v | .[0:2] |= (
[.,[$W,$H],$v] | transpose | map(add)
| .[0] %= $W | .[1] %= $H
)))
| (.b|sig) as $sig |
if $sig < .min then
.min = $sig | .bmin = .b | .smin = $s
end | debug($s)
)
| debug(
# Contrary to original hypothesis that the easter egg #
# happens in one of the quandrants, it occurs almost bang #
# in the center, but this is still somehow the min product #
reduce .bmin[] as [$x,$y] ([range($H)| [range($W)| " "]];
.[$y][$x] = "█"
) |
.[] | add
)
| .smin + 1 # Our easter egg step
And a bonus tree:
I liked day 13, a bit easy but in the right way.
Edit:
Spoilers
Although saying "minimum" was a bit evil when all of the systems had exactly 1 solution (not necessarily in ℕ^2),
I wonder if it's puzzle trickiness, anti-LLM (and unfortunate non comp-sci souls) trickiness or if the puzzle was maybe scaled down from a version where there are more solutions.
re:followup
If you somehow wanted your whole final array it would also require over 1 Peta byte ^^, memoization definetely reccomended.
Day 11
Some hacking required to make JQ work on part 2 for this one.
Part 1, bruteforce blessedly short
#!/usr/bin/env jq -n -f
last(limit(1+25;
[inputs] | recurse(map(
if . == 0 then 1 elif (tostring | length%2 == 1) then .*2024 else
tostring | .[:length/2], .[length/2:] | tonumber
end
))
)|length)
Part 2, some assembly required, batteries not included
#!/usr/bin/env jq -n -f
reduce (inputs|[.,0]) as [$n,$d] ({}; debug({$n,$d,result}) |
def next($n;$d): # Get next # n: number, d: depth #
if $d == 75 then 1
elif $n == 0 then [1 ,($d+1)]
elif ($n|tostring|length%2) == 1 then [($n * 2024),($d+1)]
else # Two new numbers when number of digits is even #
$n|tostring| .[0:length/2], .[length/2:] | [tonumber,$d+1]
end;
# Push onto call stack #
.call = [[$n,$d,[next($n;$d)]], "break"] |
last(label $out | foreach range(1e9) as $_ (.;
# until/while will blow up recursion #
# Using last-foreach-break pattern #
if .call[0] == "break" then break $out
elif
all( # If all next calls are memoized #
.call[0][2][] as $next
| .memo["\($next)"] or ($next|type=="number"); .
)
then
.memo["\(.call[0][0:2])"] = ([ # #
.call[0][2][] as $next # Memoize result #
| .memo["\($next)"] // $next # #
] | add ) | .call = .call[1:] # Pop call stack #
else
# Push non-memoized results onto call stack #
reduce .call[0][2][] as [$n,$d] (.;
.call = [[$n,$d, [next($n;$d)]]] + .call
)
end
))
# Output final sum from items at depth 0
| .result = .result + .memo["\([$n,0])"]
) | .result
I remember being quite ticked off by her takes about free will, and specifically severly misrepresenting compatibilism and calling philosphers stupid for coming up with the idea.
One look day 9 and I had to leave it until after work (puzzles unlock at 2PM for me), it wasn't THAT hard, but I had to leave it until later.
re:10
Mwahaha I'm just lazy and did are "unique" (single word dropped for part 2) of start/end pairs.
#!/usr/bin/env jq -n -R -f
([
inputs/ "" | map(tonumber? // -1) | to_entries
] | to_entries | map( # '.' = -1 for handling examples #
.key as $y | .value[]
| .key as $x | .value | { "\([$x,$y])":[[$x,$y],.] }
)|add) as $grid | # Get indexed grid #
[
($grid[]|select(last==0)) | [.] | # Start from every '0' head
recurse( #
.[-1][1] as $l | # Get altitude of current trail
( #
.[-1][0] #
| ( .[0] = (.[0] + (1,-1)) ), #
( .[1] = (.[1] + (1,-1)) ) #
) as $np | # Get all possible +1 steps
if $grid["\($np)"][1] != $l + 1 then
empty # Drop path if invalid
else #
. += [ $grid["\($np)"] ] # Build path if valid
end #
) | select(last[1]==9) # Only keep complete trails
| . |= [first,last] # Only Keep start/end
]
# Get score = sum of unique start/end pairs.
| group_by(first) | map(unique|length) | add
Hacky Manual parallelization
22-b.jqMassive time gains with parallelization + optimized next function (2x speedup) by doing the 3 xor operation in "one operation", Maybe I prefer the grids ^^: