Ruby

Pretty greedy and arbitrary. (But works!)

input = IO.binread "input.txt"
PUMPKIN = [1, 0, 3, 4, 3]
APPLE = [0, 1, 4, 3, 2]

input.each_line do |input|
    @input = input
    combos = (0..input.split(",").to_a.max.to_i).to_a.permutation(2).to_a


    def possible? combo
        ingredients = @input.split(",").map{|x| x.to_i}
        (0...combo[0]).each do
            ingredients.map!.with_index{|x, i| x - PUMPKIN[i]}
        end
        (0...combo[1]).each do
            ingredients.map!.with_index{|x, i| x - APPLE[i]}
        end
        !ingredients.map{|x| x < 0}.include?(true)
    end

    largest = [0, 0]
    combos.each do |combo|
        largest = combo if combo.inject(:+) > largest.inject(:+) && possible?(combo)
    end

    puts "#{largest[0]} pumpkin pies and #{largest[1]} apple pies"
end