Rosetta Code

Permutations

Generate every permutation of three items with a simple recursive backtracking routine.

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Sourcerosettacode/popular/permutations.vibe
def remove_at(values: array<string>, skip_index: int) -> array<string>
  output: array<string> = []
  index = 0

  while index < values.length
    if index != skip_index
      output.push(values.fetch(index))
    end
    index = index + 1
  end

  output
end

def permutations(values: array<string>) -> array<array<string>>
  if values.empty?
    return [[]]
  end

  output: array<array<string>> = []
  index = 0

  while index < values.length
    current = values.fetch(index)
    tails = permutations(remove_at(values, index))
    tail_index = 0
    while tail_index < tails.length
      output.push([current] + tails.fetch(tail_index))
      tail_index = tail_index + 1
    end
    index = index + 1
  end

  output
end

def run -> { count: int, permutations: array<array<string>> }
  values = permutations(["A", "B", "C"])
  {
    count: values.length,
    permutations: values
  }
end

Output

Click Run example to see the result.

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