Created
April 22, 2024 16:15
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Checa se delimitadores em uma string estão balanceados.
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defmodule BalancedOctopus do | |
@opening_to_closing %{"(" => ")", "[" => "]", "{" => "}"} | |
@closing_to_opening %{")" => "(", "]" => "[", "}" => "{"} | |
def balanced?(text, stack \\ []) | |
def balanced?("", []), do: true | |
def balanced?(_text, :error), do: false | |
def balanced?("", _pending_stack), do: false | |
def balanced?(text, stack) do | |
{current_char, next_text} = String.split_at(text, 1) | |
updated_stack = maybe_stack(stack, current_char) | |
balanced?(next_text, updated_stack) | |
end | |
defp maybe_stack(stack, char) do | |
cond do | |
Map.has_key?(@opening_to_closing, char) -> | |
stack_push(stack, char) | |
Map.has_key?(@closing_to_opening, char) -> | |
{last_opening, rest} = stack_pop(stack) | |
required_last_opening = @closing_to_opening[char] | |
if last_opening == required_last_opening, do: rest, else: :error | |
true -> | |
stack | |
end | |
end | |
defp stack_push(stack, inserting), do: [inserting | stack] | |
defp stack_pop([]), do: {nil, []} | |
defp stack_pop([popped | rest] = _stack), do: {popped, rest} | |
end | |
[ | |
["abcd", true], | |
["(abcd", false], | |
["(abcd)", true], | |
["(ab[cd)ef]", false], | |
["(abc[%def])", true], | |
["$(abc[de]fg{hi}jk)%//", true], | |
["(({abc})", false] | |
] | |
|> Enum.each(fn [text, expectation] -> | |
IO.write("Testing #{text} as #{expectation}... ") | |
if BalancedOctopus.balanced?(text) == expectation do | |
IO.puts("✅") | |
else | |
IO.puts("🔴") | |
end | |
end) |
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