Day2/Day2

local inputString = require(script.Input)
local inputStringArray = inputString:split(",")

local ADD = 1
local MULTIPLY = 2

local opFunctions = {
	[ADD] = function(input1, input2)
		return input1 + input2
	end,
	[MULTIPLY] = function(input1, input2)
		return input1 * input2
	end,
}

function executeOp(array, opcode, input1Pointer, input2Pointer, returnPointer)
	local input1 = array[input1Pointer]
	local input2 = array[input2Pointer]

	array[returnPointer] = opFunctions[opcode](input1, input2)
end

function executeProgram(opArray)
	for i = 1, #opArray, 4 do
		local opcode = opArray[i]
		local input1Pointer = opArray[i+1] + 1
		local input2Pointer = opArray[i+2] + 1
		local returnPointer = opArray[i+3] + 1

		if opcode == 99 then
			return opArray[1]
		end

		executeOp(opArray, opcode, input1Pointer, input2Pointer, returnPointer)
	end
end

local function getInput(noun, verb)
	local inputArray = {}

	for k,v in ipairs(inputStringArray) do
		table.insert(inputArray, tonumber(v))
	end
	
	inputArray[2] = noun
	inputArray[3] = verb
	
	return inputArray
end

-- part 1 solution
local inputArray = getInput(12, 2)
local output = executeProgram(inputArray)
print("Part 1 solution:", output)

-- part 2 solution
local desiredOutput = 19690720

-- BRUTE FORCE
for noun = 0, 99 do
	for verb = 0, 99 do
		local output = executeProgram(getInput(noun, verb))
		
		if output == desiredOutput then
			print("Noun and verb are:", noun, verb)
			local solution = 100 * noun + verb
			print("Part 2 solution:", solution)
		end
	end
end