local instructions = {}

for line in io.lines(arg[1]) do

local ins, arg = line:match("^(%w+) ([%-%+]+[0-9]+)$")

table.insert(instructions, {ins, arg})

end

function toggle(instruction)

if instruction[1] == "jmp" then

instruction[1] = "nop"

elseif instruction[1] == "nop" then

instruction[1] = "jmp"

end

end

function simulate(instructions, backtrace, pc, acc)

acc = acc or 0

pc = pc or 1

local visits = {}

local machine = {

["nop"] = function(arg) pc = pc + 1 end,

["acc"] = function(arg) acc = acc + arg pc = pc + 1 end,

["jmp"] = function(arg) pc = pc + arg end

}

while visits[pc] == nil and (pc ~= #instructions) do

table.insert(backtrace, {pc, acc})

visits[pc] = true

local ins = instructions[pc][1]

local arg = instructions[pc][2]

machine[ins](arg)

end

table.insert(backtrace, {pc, acc})

return acc

end

function part1(instructions, bc)

return simulate(instructions, bc)

end

function part2(instructions, bc)

for i, b in ipairs(bc) do

if instructions[b[1]][1] ~= "acc" then

local new_bc = {}

toggle(instructions[b[1]])

local acc = simulate(instructions, new_bc, b[1], b[2])

toggle(instructions[b[1]])

if new_bc[#new_bc][1] == #instructions then

return acc

end

end

end

end

local bc = {}

local answer1 = part1(instructions, bc)

local answer2 = part2(instructions, bc)

print(answer1)

print(answer2)