-- The function get_name() should return a single string that is the name of the puzzle.
--
function get_name()
	return "GREATEST COMMON DIVISOR"
end

-- The function get_description() should return an array of strings, where each string is
-- a line of description for the puzzle. The text you return from get_description() will 
-- be automatically formatted and wrapped to fit inside the puzzle information box.
--
function get_description()
	return { "READ VALUES FROM IN.A AND IN.B", "WRITE THE LARGEST INTEGER TO OUT.GCD THAT EVENLY DIVIDES INTO IN.A AND IN.B" }
end

-- The function get_streams() should return an array of streams. Each stream is described
-- by an array with exactly four values: a STREAM_* value, a name, a position, and an array
-- of integer values between -999 and 999 inclusive.
--
-- STREAM_INPUT: An input stream containing up to 39 numerical values.
-- STREAM_OUTPUT: An output stream containing up to 39 numerical values.
-- STREAM_IMAGE: An image output stream, containing exactly 30*18 numerical values between 0
--               and 4, representing the full set of "pixels" for the target image.
--
-- NOTE: Arrays in Lua are implemented as tables (dictionaries) with integer keys that start
--       at 1 by convention. The sample code below creates an input array of 39 random values
--       and an output array that doubles all of the input values.
--
-- NOTE: To generate random values you should use math.random(). However, you SHOULD NOT seed
--       the random number generator with a new seed value, as that is how TIS-100 ensures that
--       the first test run is consistent for all users, and thus something that allows for the
--       comparison of cycle scores.
--
-- NOTE: Position values for streams should be between 0 and 3, which correspond to the far
--       left and far right of the TIS-100 segment grid. Input streams will be automatically
--       placed on the top, while output and image streams will be placed on the bottom.
--
function gcd(a,b)
	if b ~= 0 then
		return gcd(b, a % b)
	else
		return math.abs(a)
	end
end
function get_streams()
	inputa = {}
	inputb = {}
	output = {}
	ones = 0
	one = 0
	for i = 1,39 do
		-- inner loop is so we don't have too many gcd=1 results
		-- which are horribly slow and uninteresting
		repeat
			inputa[i] = math.random(10, 99)
			inputb[i] = math.random(inputa[i], 99)
			output[i] = gcd(inputa[i], inputb[i])
			if output[i]==1 then
				one = 1
			else
				one = 0
			end
		until 1.0*(ones+one)/i < 0.4
		ones = ones + one
	end
	return {
		{ STREAM_INPUT, "IN.A", 1, inputa },
		{ STREAM_INPUT, "IN.B", 2, inputb },
		{ STREAM_OUTPUT, "OUT.GCD", 2, output },
	}
end

-- The function get_layout() should return an array of exactly 12 TILE_* values, which
-- describe the layout and type of tiles found in the puzzle.
--
-- TILE_COMPUTE: A basic execution node (node type T21).
-- TILE_MEMORY: A stack memory node (node type T30).
-- TILE_DAMAGED: A damaged execution node, which acts as an obstacle.
--
function get_layout()
	return { 
		TILE_COMPUTE, 	TILE_COMPUTE, 	TILE_COMPUTE, 	TILE_COMPUTE,
		TILE_COMPUTE, 	TILE_COMPUTE,	TILE_COMPUTE, 	TILE_COMPUTE,
		TILE_COMPUTE, 	TILE_COMPUTE,	TILE_COMPUTE, 	TILE_COMPUTE,
	}
end