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|
{presentTarget, ""} =
File.read!("inputs/day20.txt")
|> String.trim()
|> Integer.parse()
countPresents1 = fn houseNumber ->
sqrt = floor(:math.sqrt(houseNumber))
Enum.filter(1..sqrt, &(rem(houseNumber, &1) == 0))
|> Enum.map(fn lower ->
higher = div(houseNumber, lower)
if higher != lower do
(higher + lower) * 10
else
lower * 10
end
end)
|> Enum.sum()
end
[firstHouse1] =
Stream.filter(1..div(presentTarget, 10), &(countPresents1.(&1) >= presentTarget))
|> Enum.take(1)
IO.puts("First house part 1: #{firstHouse1}")
countPresents2 = fn houseNumber ->
sqrt = floor(:math.sqrt(houseNumber))
Enum.filter(1..sqrt, &(rem(houseNumber, &1) == 0))
|> Enum.map(fn lower ->
higher = div(houseNumber, lower)
lowerDeliveries =
if higher < 50 do
lower
else
0
end
higherDeliveries =
if lower < 50 do
higher
else
0
end
if higher != lower do
(lowerDeliveries + higherDeliveries) * 11
else
lowerDeliveries * 11
end
end)
|> Enum.sum()
end
[firstHouse2] =
Stream.filter(1..div(presentTarget, 10), &(countPresents2.(&1) >= presentTarget))
|> Enum.take(1)
IO.puts("First house part 2: #{firstHouse2}")
|
