Day 21: – AoC 22

# there is a comma in citizenstatezip as well
stream =
  "./input/21.txt"
  |> Path.expand(__DIR__)
  |> File.stream!()
  |> Stream.map(&String.trim(&1))

test_stream = "root: pppw + sjmn
dbpl: 5
cczh: sllz + lgvd
zczc: 2
ptdq: humn - dvpt
dvpt: 3
lfqf: 4
humn: 5
ljgn: 2
sjmn: drzm * dbpl
sllz: 4
pppw: cczh / lfqf
lgvd: ljgn * ptdq
drzm: hmdt - zczc
hmdt: 32" |> String.trim() |> String.split("\n")

Part One

%{nums: nums, terms: terms} =
  Enum.reduce(stream, %{terms: [], nums: %{}}, fn cmd, %{terms: terms, nums: nums} ->
    [var, body] = String.split(cmd, ": ")

    if String.contains?(body, ["+", "-", "/", "*"]) do
      [lhs, op, rhs] = String.split(body, " ")
      terms = [%{var: var, lhs: lhs, op: op, rhs: rhs} | terms]
      %{terms: terms, nums: nums}
    else
      nums = Map.put_new(nums, var, String.to_integer(body))
      %{terms: terms, nums: nums}
    end
  end)

iterate = fn terms, nums ->
  terms
  |> Stream.map(fn term ->
    term
    |> Map.put(
      :rhs,
      if(Enum.member?(Map.keys(nums), term.rhs), do: Map.get(nums, term.rhs), else: term.rhs)
    )
    |> Map.put(
      :lhs,
      if(Enum.member?(Map.keys(nums), term.lhs), do: Map.get(nums, term.lhs), else: term.lhs)
    )
  end)
  |> Enum.reduce(%{nums: nums, terms: []}, fn term, %{nums: nums, terms: terms} ->
    lhs = Map.get(term, :lhs)
    rhs = Map.get(term, :rhs)
    # after / it can be a float -> number
    if is_number(lhs) && is_number(rhs) do
      new_value =
        case term.op do
          "+" -> lhs + rhs
          "-" -> lhs - rhs
          # prevents floats
          "/" -> round(lhs / rhs)
          "*" -> lhs * rhs
        end

      nums = Map.put(nums, term.var, new_value)
      %{nums: nums, terms: terms}
    else
      terms = [term | terms]
      %{nums: nums, terms: terms}
    end
  end)
end

Stream.iterate(1, &(&1 + 1))
|> Enum.reduce_while(%{nums: nums, terms: terms}, fn _x, acc ->
  if Enum.count(acc.terms) <= 0 do
    {:halt, acc}
  else
    {:cont, iterate.(acc.terms, acc.nums)}
  end
end)
|> Map.get(:nums)
|> Map.get("root")

Part Two

%{nums: nums, terms: terms} =
  Enum.reduce(stream, %{terms: [], nums: %{}}, fn cmd, %{terms: terms, nums: nums} ->
    [var, body] = String.split(cmd, ": ")

    if String.contains?(body, ["+", "-", "/", "*"]) do
      [lhs, op, rhs] = String.split(body, " ")
      op = if var == "root", do: "=", else: op
      terms = [%{var: var, lhs: lhs, op: op, rhs: rhs} | terms]
      %{terms: terms, nums: nums}
    else
      nums = Map.put_new(nums, var, String.to_integer(body))
      %{terms: terms, nums: nums}
    end
  end)

iterate2 = fn terms, nums ->
  terms
  |> Stream.map(fn term ->
    term
    |> Map.put(
      :rhs,
      if(Enum.member?(Map.keys(nums), term.rhs), do: Map.get(nums, term.rhs), else: term.rhs)
    )
    |> Map.put(
      :lhs,
      if(Enum.member?(Map.keys(nums), term.lhs), do: Map.get(nums, term.lhs), else: term.lhs)
    )
  end)
  |> Enum.reduce(%{nums: nums, terms: []}, fn term, %{nums: nums, terms: terms} ->
    lhs = Map.get(term, :lhs)
    rhs = Map.get(term, :rhs)
    # after / it can be a float -> number
    if is_number(lhs) && is_number(rhs) do
      new_value =
        case term.op do
          "+" -> lhs + rhs
          "-" -> lhs - rhs
          # prevents floats
          "/" -> round(lhs / rhs)
          "*" -> lhs * rhs
          "=" -> lhs == rhs
        end

      nums = Map.put(nums, term.var, new_value)
      %{nums: nums, terms: terms}
    else
      terms = [term | terms]
      %{nums: nums, terms: terms}
    end
  end)
end

nums = Map.put(nums, "humn", 0)

Stream.iterate(2240, &(&1 + 1))
|> Enum.reduce_while(nil, fn x, _acc ->
  new_nums = Map.put(nums, "humn", Map.get(nums, "humn") + x)
  # new_acc = Map.put(acc, :nums, new_nums)

  result =
    Stream.iterate(1, &(&1 + 1))
    |> Enum.reduce_while(%{nums: new_nums, terms: terms}, fn _y, acc ->
      cond do
        # Enum.count(acc.terms) <= 0 && Map.get(acc.nums, "root") -> {:halt, acc}
        # new try
        Enum.count(acc.terms) <= 0 -> {:halt, acc}
        true -> {:cont, iterate2.(acc.terms, acc.nums)}
      end
    end)
    |> Map.get(:nums)

  if Map.get(result, "root") do
    {:halt, result}
  else
    {:cont, nil}
  end
end)
|> Map.get("humn")