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advent-of-code/2024/ruby/day_17.rb

121 lines
2.3 KiB

registers, program = DATA.read.split("\n\n")
def run(a, b, c, program)
return enum_for(__method__, a, b, c, program) unless block_given?
combo = ->(operand) {
case operand
when 0, 1, 2, 3 then operand
when 4 then a
when 5 then b
when 6 then c
else
fail
end
}
ip = 0
while (0...program.size).cover?(ip)
opcode = program.fetch(ip)
operand = program.fetch(ip+1)
case opcode
when 0
a = (a / 2**combo[operand]).to_i
ip += 2
when 1
b = b ^ operand
ip += 2
when 2
b = combo[operand] % 8
ip += 2
when 3
if a.zero?
ip += 2
else
ip = operand
end
when 4
b = b ^ c
ip += 2
when 5
yield combo[operand] % 8
ip += 2
when 6
b = (a / 2**combo[operand]).to_i
ip += 2
when 7
c = (a / 2**combo[operand]).to_i
ip += 2
else
fail
end
end
end
a, b, c = registers.scan(/\d+/).map(&:to_i)
program = program.scan(/\d+/).map(&:to_i)
# puts (211000000..).find {|a|
# pp a if a % 100_000 == 0
# program.each.lazy.zip(run(a, b, c, program)).all? { _1 == _2 }
# }
def run(a)
return enum_for(__method__, a) unless block_given?
# 14: 3 0 # jnz
until a.zero?
# 0: 2 4 # bst
# 2: 1 2 # bxl
# b = ((a & 0b111) ^ 0b010)
# 4: 7 5 # cdv
# c = a >> ((a & 0b111) ^ 0b010)
# 8: 1 7 # bxl
# 10: 4 1 # bxc
# b = ((a & 0b111) ^ 0b010) ^ c ^ 0b111
# b = ((a & 0b111) ^ 0b010) ^ (a >> ((a & 0b111) ^ 0b010)) ^ 0b111
b = (a & 0b111) ^ 0b101 ^ (a >> ((a & 0b111) ^ 0b010))
# 12: 5 5 # out
yield b & 0b111
# 6: 0 3 # adv
a >>= 3
end
end
def run(a)
return enum_for(__method__, a) unless block_given?
a.to_s(8).chars.map(&:to_i).reverse.map.with_index {|x,i|
yield (x ^ 0b101 ^ (a >> 3*i >> (x ^ 0b010))) & 0b111
}
end
pp run(27334280).to_a.join(?,)
TARGET = "2412750317415530".chars.map(&:to_i)
def solve(a)
return [a] if a.size == 16
(0..7)
.map { a + [_1] }
.select {|a|
TARGET.reverse[0,a.size].zip(
run(a.join.ljust(14, ?0).to_i(8)).to_a.reverse
).all? { _1 == _2 }
}.flat_map { solve(_1) }
end
pp solve([]).map(&:join).map { _1.to_i(8) }.min
pp run(190615597431823).to_a == program
__END__
Register A: 27334280
Register B: 0
Register C: 0
Program: 2,4,1,2,7,5,0,3,1,7,4,1,5,5,3,0