# Day 17
```elixir
Mix.install([
{:kino, "~> 0.6.2"},
{:vega_lite, "~> 0.1.5"}
])
```
## Input
```elixir
[_, ranges] = "target area: x=79..137, y=-176..-117" |> String.split(": ", trim: true)
["x", xmin, xmax, "y", ymin, ymax] = String.split(ranges, [", ", "=", ".."])
[xmin, xmax, ymin, ymax] = [xmin, xmax, ymin, ymax] |> Enum.map(&String.to_integer(&1))
range = {xmin, xmax, ymin, ymax}
print_target = fn {xmin, xmax, ymin, ymax}, locations ->
{dxmin, dxmax, dymin, dymax} = {min(xmin, 0), max(xmax, 0), min(ymin, 0), max(ymax, 0)}
{dxmin, dxmax, dymin, dymax} =
{
min(dxmin, locations |> Enum.map(&elem(&1, 0)) |> Enum.min()),
max(dxmax, locations |> Enum.map(&elem(&1, 0)) |> Enum.max()),
min(dymin, locations |> Enum.map(&elem(&1, 1)) |> Enum.min()),
max(dymax, locations |> Enum.map(&elem(&1, 1)) |> Enum.max())
}
|> IO.inspect()
for y <- dymax..dymin do
for x <- dxmin..dxmax do
cond do
{x, y} == {0, 0} ->
'S'
{x, y} in locations ->
'*'
x >= xmin and x <= xmax and y >= ymin and y <= ymax ->
'T'
true ->
'.'
end
end
|> Enum.concat()
|> IO.puts()
end
end
```
## Part 1
```elixir
path = fn {vx, vy}, {x, y} = pos, f ->
if x <= xmax and y >= ymin do
x = x + vx
y = y + vy
vx = if(vx == 0, do: 0, else: (abs(vx) - 1) * Integer.floor_div(vx, abs(vx)))
vy = vy - 1
[pos | f.({vx, vy}, {x, y}, f)]
else
[]
end
end
vxopt = round(:math.sqrt(xmin + 1) + 1)
vyopt = -ymin - 1
# print_target.(range, path.({vxopt, vyopt}, {0, 0}, path) |> IO.inspect())
hits = fn {xmin, xmax, ymin, ymax}, path ->
for {x, y} <- path do
x >= xmin and x <= xmax and y >= ymin and y <= ymax
end
|> Enum.any?()
end
ymax = round(vyopt * (vyopt + 1) / 2)
```
## Part 2
```elixir
vxmin = round(:math.sqrt(xmin + 1) + 1)
vxmax = xmax
vymin = ymin
vymax = -ymin - 1
for vx <- vxmin..vxmax,
vy <- vymin..vymax do
hits.(range, path.({vx, vy}, {0, 0}, path))
end
|> Enum.filter(& &1)
|> Enum.count()
```
