Day 1: The Tyranny of the Rocket Equation

In [1]:

    

inputLines = lines <$> readFile "input/day1.txt"


    

In [2]:

    

fuelRequired1 :: Int -> Int
fuelRequired1 mass = (mass `div` 3) - 2


    

In [3]:

    

fuelRequired1 12 == 2 && fuelRequired1 14 == 2 && fuelRequired1 1969 == 654 && fuelRequired1 100756 == 33583


    

    






True

In [4]:

    

sum <$> map (fuelRequired1 . read) <$> inputLines


    

    






3271994

In [5]:

    

fuelRequired2 :: Int -> Int
fuelRequired2 mass
    | fuel <= 0 = 0
    | otherwise = fuel + fuelRequired2 fuel
    where fuel = fuelRequired1 mass


    

In [6]:

    

fuelRequired2 14 == 2 && fuelRequired2 1969 == 966 && fuelRequired2 100756 == 50346


    

    






True

In [7]:

    

sum <$> map (fuelRequired2 .read) <$> inputLines


    

    






4905116

In [8]:

    

sum . map (sum . takeWhile (>=0) . tail . iterate fuelRequired1 . read) <$> inputLines


    

    






4905116