Rosetta Code

Smith numbers

Detect Smith numbers by comparing the digit sum of a composite integer with the digit sum of its prime factors.

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Sourcerosettacode/popular/smith_numbers.vibe
def digit_sum(value: int) -> int
  total = 0
  current = value.abs

  while current > 0
    total = total + (current % 10)
    current = current // 10
  end

  total
end

def prime?(number: int) -> bool
  if number < 2
    return false
  end

  candidate = 2
  while candidate * candidate <= number
    if number % candidate == 0
      return false
    end
    candidate = candidate + 1
  end

  true
end

def factor_digit_sum(number: int) -> int
  total = 0
  remaining = number
  factor = 2

  while factor * factor <= remaining
    while remaining % factor == 0
      total = total + digit_sum(factor)
      remaining = remaining // factor
    end
    factor = factor + 1
  end

  if remaining > 1
    total = total + digit_sum(remaining)
  end

  total
end

def smith?(number: int) -> bool
  if prime?(number)
    return false
  end

  digit_sum(number) == factor_digit_sum(number)
end

def run -> array<{ smith: bool, value: int }>
  [
    { value: 4, smith: smith?(4) },
    { value: 22, smith: smith?(22) },
    { value: 27, smith: smith?(27) },
    { value: 58, smith: smith?(58) },
    { value: 85, smith: smith?(85) },
    { value: 13, smith: smith?(13) }
  ]
end

Output

Click Run example to see the result.

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