AoC19/lib/day5/day5.ex

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Elixir
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2019-12-05 18:34:06 +00:00
defmodule Day5 do
def read_program do
File.read!("lib/day5/input.txt")
|> String.trim()
|> String.split(",")
|> Enum.map(&String.to_integer/1)
end
def run_program do
read_program()
|> run()
end
def test do
run([
3,
21,
1008,
21,
8,
20,
1005,
20,
22,
107,
8,
21,
20,
1006,
20,
31,
1106,
0,
36,
98,
0,
0,
1002,
21,
125,
20,
4,
20,
1105,
1,
46,
104,
999,
1105,
1,
46,
1101,
1000,
1,
20,
4,
20,
1105,
1,
46,
98,
99
])
end
def run(memory, ip \\ 0)
def run(memory, ip) when ip < length(memory) do
IO.inspect(memory)
case eval(Enum.drop(memory, ip), memory) do
{memory, :halt} ->
memory
{memory, :cont, offset} ->
run(memory, ip + offset)
{memory, :jump, ip} ->
run(memory, ip)
end
end
def run(memory, _ip), do: memory
defmacro opcode(op, expected) do
quote do
rem(unquote(op), 100) == unquote(expected)
end
end
def get_param(op, param, val, memory) do
place = param + 2
if op |> div(pow(10, place)) |> rem(10) == 1 do
val
else
Enum.at(memory, val)
end
end
def pow(base, 1), do: base
def pow(base, exp) do
base * pow(base, exp - 1)
end
# halt
def eval([99 | _], memory) do
{memory, :halt}
end
# add
def eval([op, a, b, dest | _], memory) when opcode(op, 1) do
a_val = get_param(op, 0, a, memory)
b_val = get_param(op, 1, b, memory)
{
List.replace_at(memory, dest, a_val + b_val),
:cont,
4
}
end
# multiply
def eval([op, a, b, dest | _], memory) when opcode(op, 2) do
a_val = get_param(op, 0, a, memory)
b_val = get_param(op, 1, b, memory)
{
List.replace_at(memory, dest, a_val * b_val),
:cont,
4
}
end
# input
def eval([3, addr | _], memory) do
res = IO.gets("intcode> ") |> String.trim() |> String.to_integer()
{
List.replace_at(memory, addr, res),
:cont,
2
}
end
# output
def eval([op, param | _], memory) when opcode(op, 4) do
get_param(op, 0, param, memory) |> IO.inspect()
{memory, :cont, 2}
end
# jump if non-zero
def eval([op, condition, ip | _], memory) when opcode(op, 5) do
case get_param(op, 0, condition, memory) do
0 ->
{memory, :cont, 3}
_ ->
{memory, :jump, get_param(op, 1, ip, memory)}
end
end
# jump if zero
def eval([op, condition, ip | _], memory) when opcode(op, 6) do
case get_param(op, 0, condition, memory) do
0 ->
{memory, :jump, get_param(op, 1, ip, memory)}
_ ->
{memory, :cont, 3}
end
end
# less than
def eval([op, a, b, dest | _], memory) when opcode(op, 7) do
a_val = get_param(op, 0, a, memory)
b_val = get_param(op, 1, b, memory)
memory =
if a_val < b_val do
List.replace_at(memory, dest, 1)
else
List.replace_at(memory, dest, 0)
end
{memory, :cont, 4}
end
# equals
def eval([op, a, b, dest | _], memory) when opcode(op, 8) do
a_val = get_param(op, 0, a, memory)
b_val = get_param(op, 1, b, memory)
memory =
if a_val == b_val do
List.replace_at(memory, dest, 1)
else
List.replace_at(memory, dest, 0)
end
{memory, :cont, 4}
end
end